הרמב"ם והרמב"ן נחלקים ביניהם בשאלת היחס בין הפשט לדרש. הרמב"ם בשורש השני מתייחס לבה"ג שכולל במניין המצוות שלו גם הלכות שנלמדות מדרשות, וכותב:
וכבר הגיעו בזה הסכלות אל יותר קשה מזה, וזה כשמצאו דרש בפסוק יתחייב בדרש ההוא לעשות פעולות או או להרחיק ענין מן הענינים והם כלם בלי ספק מדרבנן ימנו אותם בכלל המצות ואע"פ שפשטיה דקרא לא יורה על דבר מאותם הענינים עם השרש שהועילונו בו ע"ה והוא אמרם ז"ל אין מקרא יוצא מידי פשוטו, והיות התלמוד בכל מקום ישאל פשטיה דקרא במאי כתיב כשמצאו פסוק ילמדו ממנו על צד הבאור והראיה דברים רבים.
איך למד הרמב"ם את משמעות הביטוי התלמודי "אין מקרא יוצא מידי פשוטו"?
ראו בהמשך דבריו שם:
[ואולי תחשוב שאני בורח מלמנותן להיותן בלתי אמתיות והיות הדין היוצא במדה ההיא אמת או בלתי אמת, אין זו הסבה. אבל הסבה כי כל מה שיוציא אדם ענפים מן השרשים שנאמרו לו למשה בסיני בבאור והם תרי"ג מצות ואפילו היה המוציא משה בעצמו אין ראוי למנותם.
לעומת זאת, הרמב"ן בהשגותיו לשורש השני חולק עליו בתקיפות:
והנה הרב תלה הר נופל הזה בחוט השערה. אמר העיקר אשר הועילונו בו ע"ה והוא אמרם אין מקרא יוצא מידי פשוטו והיות לשון התלמוד מחפש בכל מקום ואומר גופיה דקרא במאי משתעי. וחס ושלום כי המדרשים כולם בענין המצות אין בהם מקרא יוצא להם מידי פשוטו אלא כולם בלשון הכתוב נכללים. אע"פ שהם מרבים בהם בריבויים
ואין מדרש כבוד תלמידי חכמים מלשון את ה' אלהיך תירא מוציא הכתוב מפשוטו. וכן אם נאמר בכי יקח איש אשה שהוא בכסף אינו מוציא ממשמעו ופשטו. ולא כל אתי"ן וגמי"ן ריבויין ואכי"ן ורקי"ן מיעוטין ושאר המדרשים כולם
אבל הכתוב יכלול הכל כי אין הפשט כלשון חסרי הדעת ולא כדעת הצדוקים כי ספר תורת ה' תמימה אין בה אות יתר וחסר כולם בחכמה נכתבו.
וכן הענין בכ"מ הנדרש להם בענין משל ומליצה יאמינו כי שניהם אמת פנימי וחיצון... והוא מאמרם אין המקרא יוצא מידי פשוטו, לא אמרו אין מקרא אלא כפשוטו אבל יש לנו מדרשו עם פשוטו ואינו יוצא מידי כל אחד מהם אבל יסבול הכתוב את הכל ויהיו שניהם אמת.
מורה נבוכים ח"ג פמ"א
מי שחיסר איבר יחוסר איבר כמותו: "כאשר יתן מום באדם כן ינתן בו" (ויקרא כד, כ). אל תעסיק מחשבתך בזה שאנו עונשים כאן בתשלומים, כי מטרתי עכשיו לתת טעמים לכתובים ולא לתת טעמים להלכה, אף שגם על הלכה זאת יש לי דעה שאותה אשמיע בעל פה.
מה עולה מכאן לגבי היחס בין פשט לדרש?
השוו גם לדברי הרמב"ם בהל' חובל ומזיק
זֶה שֶׁנֶּאֱמַר בַּתּוֹרָה (ויקרא כד כ) "כַּאֲשֶׁר יִתֵּן מוּם בָּאָדָם כֵּן יִנָּתֶן בּוֹ" אֵינוֹ לַחֲבל בָּזֶה כְּמוֹ שֶׁחָבַל בַּחֲבֵרוֹ אֶלָּא שֶׁהוּא רָאוּי לְחַסְּרוֹ אֵיבָר אוֹ לַחֲבל בּוֹ כַּאֲשֶׁר עָשָׂה וּלְפִיכָךְ מְשַׁלֵּם נִזְקוֹ.
When the Torah says: "If a man disfigures a person, as he has done so shall it be done to him" (Leviticus 24:20), it does not mean to inflict injury on this man as he did on the other, but that the offender fittingly deserves to be deprived of a limb or wounded in the same manner as he did, and must therefore indemnify the damage he caused. Furthermore, the Torah says: "You shall accept no ransom for the life of a murderer" (Numbers 35:31), implying that only for a murderer no ransom is accepted, but compensation is taken for the loss of limbs or for injuries sustained.
אחד מראשי המדברים בסוגיית היחס בין הפשט לדרש הוא הגר"א. נביא כאן דוגמה שעוסקת בפסוק בספר משלי
דְּאָגָ֣ה בְלֶב־אִ֣ישׁ יַשְׁחֶ֑נָּה וְדָבָ֖ר ט֣וֹב יְשַׂמְּחֶֽנָּה׃
If there is anxiety in a man’s mind let him quash it, And turn it into joy with a good word.
מהי משמעות המונח "ישחנה" בפסוק הזה? הגמרא סנהדרין דורשת
(משלי יב, כה) דאגה בלב איש ישחנה ר' אמי ור' אסי חד אמר ישיחנה מדעתו וחד אמר ישיחנה לאחרים
You must say that the attribute of reward is greater than the attribute of punishment, as with regard to the attribute of reward it is written: “He commanded the clouds from above, and opened the doors of heaven, and rained upon them manna to eat” (Psalms 78:23–24). And with regard to the attribute of punishment at the time of the flood the verse says: “And the windows of the heavens were opened” (Genesis 7:11). To mete out punishment, God opened only windows, which are considerably smaller openings than doors, indicating that the attribute of reward is greater. With regard to the attribute of punishment it is written: “And they shall go forth, and look upon the carcasses of the men who have rebelled against Me; for their worm shall not die, neither shall their fire be quenched; and they shall be an abhorrence to all flesh” (Isaiah 66:24). The Gemara asks: Is it not so that when a person extends his finger into the fire in this world, he is immediately burned? How, then, can one withstand the fire of Gehenna, which is never extinguished? Rather, just as the Holy One, Blessed be He, provides strength to the wicked to receive their punishment, so too, the Holy One, Blessed be He, provides strength to the righteous to receive their reward, His handful. § The mishna teaches that Rabbi Akiva says: Also one who reads external literature has no share in the World-to-Come. The Sages taught in a baraita: This is a reference to reading books of heretics. Rav Yosef says: It is also prohibited to read the book of ben Sira, due to its problematic content. Abaye said to Rav Yosef: What is the reason that it is prohibited to read the book of ben Sira? If we say that it is prohibited due to the fact that ben Sira wrote in it: Do not flay the skin of the fish from its ear, so that its skin does not go to ruin, but roast it on the fire and eat with it two loaves of bread, and you believe it to be nonsense, that is not a sufficient reason. If your difficulty is from its literal meaning, that does not pose a difficulty, as in the Torah, God also wrote: “You shall not destroy its trees” (Deuteronomy 20:19). It is prohibited to destroy both trees and fish skin arbitrarily. If your difficulty is from its homiletic interpretation as a euphemism, ben Sira is teaching us proper conduct: A man should not engage in sexual intercourse in an atypical manner, i.e., anal intercourse, with his wife, as it causes her discomfort. Rather, perhaps the book poses a difficulty because it is written there: A daughter is for her father false treasure; due to fear for her he will not sleep at night: During her minority, lest she be seduced; during her young womanhood lest she engage in licentiousness; once she has reached her majority, lest she not marry; once she marries, lest she have no children; once she grows old, lest she engage in witchcraft (Ben Sira 42:11–14). Perhaps you believe that one should not say this to the father of daughters. Didn’t the Sages also say it with regard to women? They said: It is impossible for the world to exist without males and without females; nevertheless, happy is one whose children are males and woe unto him whose children are females. Rather, perhaps the book poses a difficulty because it is written there: Do not introduce anxiety into your heart, as anxiety has killed mighty men (Ben Sira 14:1; 30:29). Didn’t Solomon already say it in the verse: “Anxiety in a man’s heart dejects him [yashḥena]” (Proverbs 12:25)? Rabbi Ami and Rabbi Asi interpret the term homiletically and read it as yesiḥenna. One says that it means: He shall remove it [yesiḥenna] from his mind, and that will ease his anxiety. And one says: He shall tell it [yesiḥenna] to others, and that will ease his anxiety. Both agree with the statement of ben Sira. Rather, perhaps the book poses a difficulty because it is written there: Prevent the multitudes from inside your house, and do not bring everyone into your house (Ben Sira 11:37). But didn’t Rabbi Yehuda HaNasi also say it, as it is taught in a baraita that Rabbi Yehuda HaNasi says: A person should never have many friends inside his house, as it is stated: “There are friends that one has to his own detriment” (Proverbs 18:24), as through his association with them he will become weak and be ruined. Rather, perhaps the book poses a difficulty because it is written there: A sparse-bearded man is clever; a thick-bearded man is a fool. One who blows on his cup is not thirsty. One who said: With what will I eat bread, take the bread from him. One who has a passage in his beard, the entire world is unable to overcome him. Abaye suggests: Due to all this nonsense, it is not appropriate to read this book. Rav Yosef says: Even though there are passages in the book that are inappropriate, we teach the superior matters that are in it even in public. A good wife is a good gift; she will be given into the bosom of a God-fearing man (Ben Sira 26:3). A bad wife is leprosy for her husband. What is his remedy? He shall chase her from his house and will be healed from his leprosy (Ben Sira 25:30). A beautiful wife, happy is her husband; the number of his days is doubled (Ben Sira 26:1). Due to his happiness, it is as though his life is twice as long. We also teach what it states there: Avert your eyes from a woman of grace, lest you be trapped in her snare. Turn not to her husband to mix wine and strong drink with him, as many have been corrupted by the beauty of the beautiful woman, and mighty are all her fatalities (Ben Sira 9:9–11). Many are the wounds of a peddler (Ben Sira 11:36), which in this context is referring to those who accustom others to matters of forbidden sexual relations. Like a spark ignites a coal (Ben Sira 11:43), like a cage full of birds, so too, their houses are filled with deceit (Ben Sira 11:36–37). Prevent the multitudes from inside your house, and do not bring everyone into your house (Ben Sira 11:37). Let many be those who greet you; reveal your secrets to one in a thousand. From she who lies in your bosom guard the openings of your mouth, i.e., do not tell her everything. Grieve not about tomorrow’s trouble, because you know not what a day may bring; perhaps tomorrow you will no longer be, and one will have worried about a world that is not his. The verse states: “All the days of the poor are terrible” (Proverbs 15:15). The book of ben Sira says: Also the nights are terrible, as then the poor person worries. The poor person’s roof is among the lowest roofs in the city, and in the elevation of the hills is his vineyard, at the highest point, as those are of the lowest quality and consequently the least expensive places for each. From the rain on the roofs of the entire city, water will flow down to his roof and dampen it, and the soil of his vineyard is eroded by the rain and swept down to other vineyards. § The Gemara provides a mnemonic for the statements that follow, based primarily on those who authored those statements. Zeira; Rava; Mesharshiyya; Ḥanina toviyya, referring to Rabbi Ḥanina, who spoke of a good [tova] wife; Yannai yafe, referring to Rabbi Yannai, who spoke of one who is broad-minded [da’ato yafe]; Yoḥanan meraḥem, referring to Rabbi Yoḥanan, who spoke of one who is compassionate [meraḥem]; Yehoshua mekatzer, referring to Rabbi Yehoshua ben Levi, who spoke of one who is intolerant [da’ato ketzara]. Rabbi Zeira says that Rav says: What is the meaning of that which is written: “All the days of the poor are terrible, and for the good-hearted it is always a feast” (Proverbs 15:15)? “All the days of the poor are terrible”; these are masters of the Talmud, who invest constant effort in their study and encounter endless difficulties and questions. “And for the good-hearted it is always a feast”; these are masters of the Mishna, who study only halakhic conclusions and encounter no difficulties. Rava says that the opposite is true; and this is that which Rav Mesharshiyya said in the name of Rava: What is the meaning of that which is written: “One who quarries stones shall be saddened by them and he who chops wood shall be warmed by it” (Ecclesiastes 10:9)? “One who quarries stones shall be saddened by them”; these are masters of the Mishna, as they invest effort, but are unable to benefit from that effort, as they do not reach halakhic conclusions. “And he who chops wood shall be warmed by it”; these are masters of the Talmud, who invest considerable effort and benefit from it, as they reach halakhic conclusions. Rabbi Ḥanina says: “All the days of the poor are terrible”; this is referring to one who has a bad wife. “And for the good-hearted it is always a feast”; this is referring to one who has a good wife. Rabbi Yannai says: “All the days of the poor are terrible”; this is referring to one who is delicate [istenis], i.e., one who is sensitive to repulsive items. “And for the good-hearted it is always a feast”; this is referring to one who is broad-minded [da’ato yafe], i.e., he is not particular and will eat anything. Rabbi Yoḥanan says: “All the days of the poor are terrible”; this is referring to one who is compassionate [meraḥem], as he always senses the suffering in the world and is constantly anxious. “And for the good-hearted it is always a feast”; this is referring to one who is cruel and indifferent to suffering in the world. Rabbi Yehoshua ben Levi says: “All the days of the poor are terrible”; this is referring to
ר' מנשה מאיליא, תלמיד הגר"א, מביא בהקדמת ספרו בינת מקרא, בשם הגר"א את הפירוש הבא לדרשת הגמרא:
כיצד הוא מבין את היחס בין פשט לדרש?
כעת נעיין מעט בדרשות מריבוי של "את". ראו לדוגמה את הגמרא בכתובות
דתניא כבד את אביך ואת אמך את אביך זו אשת אביך ואת אמך זו בעל אמך וי"ו יתירה לרבות את אחיך הגדול
The Gemara asks: Honoring a father’s wife is also required by Torah law, as it is taught in a baraita: Honor your father [et avikha] and your mother [ve’et immekha]. The preposition et in the phrase: Your father; this teaches that you must honor your father’s wife. Similarly, the preposition et in the phrase: And your mother; this teaches that you must honor your mother’s husband. And the extra letter vav, which is appended as a prefix in the phrase “ve’et immekha” is included in order to add your older brother to those who must be honored.
ראו עוד דוגמה בתלמוד הבבלי במסכת פסחים
ואידך את לא דריש כדתניא שמעון העמסוני ואמרי לה נחמיה העמסוני היה דורש כל אתים שבתורה כיון שהגיע לאת ה׳ אלהיך תירא פירש אמרו לו תלמידיו רבי כל אתים שדרשת מה תהא עליהן אמר להם כשם שקבלתי שכר על הדרישה כך אני מקבל שכר על הפרישה עד שבא רבי עקיבא ודרש את ה׳ אלהיך תירא לרבות תלמידי חכמים
The Gemara asks: According to Ḥizkiya, who says that: You shall not eat, indicates only that eating is prohibited but that benefit is permitted, for what halakha is blood juxtaposed to water? According to his opinion, there is no need for the verse to teach that one may benefit from blood. The Gemara answers that he needs this verse to derive that which was taught by Rabbi Ḥiyya bar Abba, as Rabbi Ḥiyya bar Abba said that Rabbi Yoḥanan said: From where is it derived that the blood of sacrifices does not render food susceptible to ritual impurity? As it is stated: “You shall not eat it; you shall pour it out upon the earth like water” (Deuteronomy 12:24). Blood that is poured out like water, such as that of a slaughtered, non-sacrificial animal, renders food susceptible to ritual impurity. However, sacrificial blood, which is not poured out like water and is instead sprinkled on the altar, does not render food susceptible to ritual impurity. The Gemara further challenges Rabbi Abbahu’s opinion: And yet there is the prohibition against eating a limb cut from a living animal, as it is written: “Only be steadfast in not eating the blood; for the blood is the life; and you shall not eat the life with the flesh” (Deuteronomy 12:23). And it was taught in a baraita that Rabbi Natan says: From where is it derived that a person may not offer a cup of wine to a nazirite, who is prohibited from drinking wine, and that he may not offer a limb cut from a living animal to a descendant of Noah, who is prohibited by Noahide law from eating a limb from a living animal? The verse states: “You shall not put a stumbling block before the blind” (Leviticus 19:14). Causing another person to sin is like placing a stumbling block before a blind person; one who does so violates this prohibition. The prohibition of giving a limb from a living animal to a gentile is apparently due only to the prohibition of placing a stumbling block. However, it is permitted for one to throw it to dogs. Therefore, despite the fact that the verse says: “You shall not eat it,” apparently there is no prohibition against benefiting from this prohibited item. This challenges Rabbi Abbahu’s principle. The Gemara answers: A limb from a living animal is different, as it is juxtaposed in the Torah to blood. As it is written: “Only be steadfast in not eating the blood; for the blood is the life; and you shall not eat the life with the flesh” (Deuteronomy 12:23). Just as it is permitted to benefit from blood, it is likewise permitted to benefit from a limb torn from a living animal. The Gemara asks: And according to Ḥizkiya, in order to teach what halakha is the prohibition against eating a limb from a living animal juxtaposed to the prohibition against eating blood? The Gemara answers: He could have said to you that the juxtaposition comes to teach the opposite. It is blood that is juxtaposed to a limb from a living animal to teach the following: Just as a limb from a living animal is prohibited, so too, blood of a living being is prohibited. And to which blood is this referring? This is referring to blood spilled in the process of bloodletting, through which the soul departs. That is considered to be blood from a living being, and even the descendants of Noah are prohibited from eating it (Rabbeinu Ḥananel). The Gemara asks: And yet there is the prohibition against eating the meat from an ox that is stoned, as the Merciful One says: “And if an ox gores a man or a woman to death, the ox shall be surely stoned, and of its flesh shall not be eaten; but the owner of the ox shall be clear” (Exodus 21:28). And it was taught in a baraita: By inference from that which is stated: “The ox shall surely be stoned,” in which case it is not to be slaughtered properly, don’t I know that it is an animal carcass, and it is prohibited to eat an animal carcass? What does it mean when the verse states: “Its flesh shall not be eaten”? The verse is telling you that even if one slaughtered the ox after its verdict had been reached but before it had been carried out, it is still prohibited. The baraita continues: I have derived only that one is prohibited from eating this ox; from where do I derive that one is prohibited from deriving benefit from it as well? The verse states: “But the owner of the ox shall be clear [naki].” The Gemara asks: From where may it be inferred that one may not benefit from this ox? Shimon ben Zoma says: This is like a person who says to his fellow: So-and-so was left clear [naki] of his property, and he has no benefit from it at all. Similarly, “But the owner of the ox shall be clear” means that he has no benefit from the ox. The Gemara infers from the verse that the reason that it is prohibited to derive benefit from the ox is that the Torah specifically wrote: “But the owner of the ox shall be clear.” As, if this prohibition were derived from: “It shall not be eaten,” apparently the prohibition of eating would be implied, but the prohibition of deriving benefit would not be implied. This presents a challenge even for Ḥizkiya, who agrees that the passive formulation: “It shall not be eaten,” indicates that in addition one may not benefit from the item. The Gemara answers: Actually, the phrase: “It shall not be eaten” indicates both a prohibition of eating and a prohibition of deriving benefit. And the phrase: “But the owner of the ox shall be clear,” comes to prohibit deriving benefit from the hide of the ox that has been stoned. And it is necessary to mention this explicitly, as it could enter your mind to say that since it is written: “Its flesh shall not be eaten,” with regard to its flesh, yes, it is prohibited, but with regard to its hide, no, it is not. Therefore, the verse teaches us that it is prohibited to benefit from its hide as well. The Gemara asks: And according to those tanna’im who expound this verse: “But the owner of the ox shall be clear,” for another interpretation, namely, to teach that the owner of an innocuous ox, i.e., one that is not known to cause damage with the intent to injure, is exempt from the payment of half of the indemnity if that ox killed a person, or that he is exempt from payment for offspring if his ox gores a pregnant woman and causes her to miscarry; from where do they derive this prohibition against benefiting from the ox’s hide? The Gemara answers: They derive this halakha from the wording: “Of [et] its flesh.” The verse could have been formulated: And its flesh shall not be eaten. The addition of the word et comes to include that which is secondary to the flesh, i.e., the hide. The Gemara asks: And the other tanna, who derives the prohibition against benefiting from the hide from the verse: “But the owner of the ox shall be clear,” what does he learn from the additional word et? The Gemara answers: This Sage does not interpret the word et as a means to derive new halakhot. He considers the word et to be an ordinary part of the sentence structure and not a source for exegetical exposition. As it was taught in a baraita: Shimon HaAmmassoni, and some say that it was Neḥemya HaAmmassoni, would interpret all occurrences of the word et in the Torah, deriving additional halakhot with regard to the particular subject matter. Once he reached the verse: “You shall be in awe of [et] the Lord your God; you shall serve Him; and to Him you shall cleave, and by His name you shall swear” (Deuteronomy 10:20), he withdrew from this method of exposition, as how could one add to God Himself? His students said to him: Rabbi, what will be with all the etim that you interpreted until now? He said to them: Just as I received reward for the interpretation, so I shall receive reward for my withdrawal from using this method of exposition. The word et in this verse was not explained until Rabbi Akiva came and expounded: “You shall be in awe of [et] the Lord your God”: The word et comes to include Torah scholars, and one is commanded to fear them just as one fears God. In any case, Shimon HaAmmassoni no longer derived additional halakhot from the word et. The Gemara further challenges: And yet there is the prohibition of fruit that grows on a tree during the first three years after it was planted [orla], as the Merciful One says: “And when you come into the land, and you shall plant all types of trees for food, then you shall count the fruit thereof as prohibited; three years shall it be prohibited [arelim] to you; it shall not be eaten” (Leviticus 19:23). And it was taught in a baraita: “Shall it be prohibited to you; it shall not be eaten”: I have only derived a prohibition to eat it. From where do I derive that one may not even benefit from it, e.g., that he may not paint with the dye that can be extracted from the fruit, nor may he light a lamp with its oil? The verse states: “You shall count the fruit thereof [orlato] as prohibited [araltem]; three years shall it be prohibited [arelim] to you; it shall not be eaten.” This repetition of the term arel comes to include all forms of benefit. The Gemara reads precisely: The reason that all forms of benefit are prohibited is that the Merciful One writes: “You shall count the fruit thereof as prohibited [araltem]; three years shall it be prohibited [arelim].” The double use of the word arel indicates a two-fold prohibition. However, were that not the case, I would have said: The prohibition of eating is indicated here; however, the prohibition to derive benefit is not indicated. This is a challenge even to Ḥizkiya’s opinion, as the verse says: “It shall not be eaten,” indicating that it is prohibited to derive benefit as well. The Gemara rejects this. Actually, in general, “it shall not be eaten” indicates both a prohibition of eating and a prohibition to derive benefit. However, it is different there, with regard to orla, as it is written: “Three years shall it be prohibited [arelim] to you.” And, therefore, it was necessary for the verse to repeat the prohibition using several terms, as it could enter your mind to say that since it wrote “to you” it means that it shall be yours, namely that one is permitted to benefit from it. Therefore, it teaches us that it is prohibited to derive benefit. The Gemara asks: However, now that these words in the verses are written, indicating the prohibition to derive benefit from orla, why do I need the words “to you,” i.e., what does this phrase teach us here? The Gemara answers: As it was taught in a baraita: That which is stated: “To you,” comes to include that which is planted
הרמב"ם בשורש השני תוקף את בה"ג שמנה את המצווה הזאת, וכותב:
וזה גם כן שרש כבר נשתבש בו זולתנו ולכן מנה יראת חכמים עם מצות עשה, ואשר הביאו לזה לפי מה שיראה לי מאמר ר' עקיבא את ה' אלהיך תירא לרבות תלמידי חכמים חשב שכל מה שיגיע משלש עשרה מדות הוא מן הכלל הנזכר, ואם היה הענין כמו שחשבו למה לא מנו כבוד בעל האם ואשת האב מצוה בפני עצמה מחוברת אל כבוד אב ואם וכן כבוד אחיו הגדול כי אלו האישים למדנו שאנו חייבין לכבדם ברבוי אמרו (כתובות ק"ג) כבד את אביך לרבות אחיך הגדול ואמרו את אביך לרבות בעל אמך ואת אמך לרבות אשת אביך כמו שאמרו את ה' אלהיך תירא לרבות תלמידי חכמים, אם כן מפני מה מנו אלו ולא מנו אלו.
ראו גם בהלכות ממרים:
(טו) חַיָּב אָדָם לְכַבֵּד אֶת אֵשֶׁת אָבִיו אַף עַל פִּי שֶׁאֵינָהּ אִמּוֹ כָּל זְמַן שֶׁאָבִיו קַיָּם שֶׁזֶּה בִּכְלַל כְּבוֹד אָבִיו. וְכֵן מְכַבֵּד בַּעַל אִמּוֹ כָּל זְמַן שֶׁאִמּוֹ קַיֶּמֶת. אֲבָל לְאַחַר מִיתָתָהּ אֵינוֹ חַיָּב. וּמִדִּבְרֵי סוֹפְרִים שֶׁיִּהְיֶה אָדָם חַיָּב בִּכְבוֹד אָחִיו הַגָּדוֹל כִּכְבוֹד אָבִיו:
(15) One is obligated to honor his father's wife, even though she is not one's mother, while his father is alive. And so too one should honor one's mother's husband while one's father is alive. After she dies the obligation ends. And from the words of our Sages, one is obligated to honor an older brother like one honors a father.
ראו את דברי הרמב"ן בהשגותיו לשורש הזה, שעונה בשמו של בה"ג:
השגות הרמב"ן על ספר המצוות
אבל אני מבאר סברתו בזה. אמרו שם בגמר כתובות הני מילי מחיים אבל לאחר מיתה לא. הנה ביארו כי זה האיש שהוא בעל אמו אינו חייב בכבודו מפני כבוד עצמו אלא מפני שהוא כבוד לאמו בענין האיש ההוא הרי זה פטור ממנו. נמצא שלא נתרבה כאן מצוה יתירה על כבוד האבות אלא שיכבד אותם בכל ענין שיהיה להם כבוד.