How do we know that truth stands on a solid foundation and that falsehood totters and will eventually fall to the ground? The very shape of the letters tells us. If we compare the letters of (emet), truth, and (sheker), falsehood, we see (with a little good will) that, where the letters meet the line, truth stands on two legs while the letters of falsehood stand on only one. - Dr. Joseph Lowen
(ז) מִדְּבַר־שֶׁ֖קֶר תִּרְחָ֑ק וְנָקִ֤י וְצַדִּיק֙ אַֽל־תַּהֲרֹ֔ג כִּ֥י לֹא־אַצְדִּ֖יק רָשָֽׁע׃
(7) Keep far from a false charge; do not bring death on those who are innocent and in the right, for I will not acquit the wrongdoer.
(יח) רַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל אוֹמֵר, עַל שְׁלשָׁה דְבָרִים הָעוֹלָם עוֹמֵד, עַל הַדִּין וְעַל הָאֱמֶת וְעַל הַשָּׁלוֹם, שֶׁנֶּאֱמַר (זכריה ח) אֱמֶת וּמִשְׁפַּט שָׁלוֹם שִׁפְטוּ בְּשַׁעֲרֵיכֶם:
(18) Rabban Shimon ben Gamliel says, "On three things the world stands: on judgment, on truth and on peace, as it is said (Zachariah 8:16), 'Judge truth and the justice of peace in your gates.'"
(ה) אָמַר רַבִּי סִימוֹן, בְּשָׁעָה שֶׁבָּא הַקָּדוֹשׁ בָּרוּךְ הוּא לִבְרֹאת אֶת אָדָם הָרִאשׁוֹן, נַעֲשׂוּ מַלְאֲכֵי הַשָּׁרֵת כִּתִּים כִּתִּים, וַחֲבוּרוֹת חֲבוּרוֹת, מֵהֶם אוֹמְרִים אַל יִבָּרֵא, וּמֵהֶם אוֹמְרִים יִבָּרֵא, הֲדָא הוּא דִכְתִיב (תהלים פה, יא): חֶסֶד וֶאֱמֶת נִפְגָּשׁוּ צֶדֶק וְשָׁלוֹם נָשָׁקוּ. חֶסֶד אוֹמֵר יִבָּרֵא, שֶׁהוּא גּוֹמֵל חֲסָדִים. וֶאֱמֶת אוֹמֵר אַל יִבָּרֵא, שֶׁכֻּלּוֹ שְׁקָרִים. צֶדֶק אוֹמֵר יִבָּרֵא, שֶׁהוּא עוֹשֶׂה צְדָקוֹת. שָׁלוֹם אוֹמֵר אַל יִבָּרֵא, דְּכוּלֵיהּ קְטָטָה. מֶה עָשָׂה הַקָּדוֹשׁ בָּרוּךְ הוּא נָטַל אֱמֶת וְהִשְׁלִיכוֹ לָאָרֶץ, הֲדָא הוּא דִכְתִיב (דניאל ח, יב): וְתַשְׁלֵךְ אֱמֶת אַרְצָה, אָמְרוּ מַלְאֲכֵי הַשָּׁרֵת לִפְנֵי הַקָּדוֹשׁ בָּרוּךְ הוּא, רִבּוֹן הָעוֹלָמִים מָה אַתָּה מְבַזֶּה תַּכְסִיס אַלְטִיכְסְיָה שֶׁלָּךְ, תַּעֲלֶה אֱמֶת מִן הָאָרֶץ, הֲדָא הוּא דִכְתִיב (תהלים פה, יב): אֱמֶת מֵאֶרֶץ תִּצְמָח.
(5) R. Simon said: When the Holy One was about to create the first human, the ministering angels formed themselves into factions and groups. Some of them said: “Let him be created.” Some of them said: Let him not be created.” This is why it is written, “Loving kindness and truth meet; justice and peace kiss” (Psalm 85:11). Loving kindness said, “Let him be created because he will perform acts of loving kindness.” Truth said, “Let him not be created because he will all falsehood.” Justice said, “Let him be created because he will do deeds of justice.” Peace said, “Let him not be created because he will be all conflict.” What did the Holy One do? He took Truth and cast him to the ground, as is written said: “You cast truth to the ground” (Daniel 8:12). The ministering angels said to the Holy One: “Master of the Universe: Why do You humiliate Your seal, lift Truth up from the earth.” Hence it is written: “Truth springs up from the earth” (Psalm 85:12).
Said Rava: I used to think there is no truth in the whole world, A certain rabbi, whose name was Rav Tvut (and some say his name is Rav Tavyomi) that if the whole world filled with gold would be given to him, he would not change his word. It happened once that he came to a city named Kushta (truth). And the inhabitants of that city would not change their word, and it never happened that one should die an untimely death. He married a woman from there and she bore him two children. It happened once that his wife was washing her hair, and a female neighbor came knocking on the door. He thought that it's not polite [to say that she's washing her hair], and therefore said that she is out. And the two children died. And when the inhabitants came to ask him what was the reason that such an unusual thing happened to him, he told them what happened. They said: please, move away and don't bring death to these people.
כלה כמות שהיא - ואם יש בה מום ישתקו ולא ישבחוה אי נמי ישבחוה בדבר נאה שיש בה כגון בעיניה או בידיה אם הם יפות וב"ה אומרים ישבחוה לגמרי דכשמזכירין מה שיש בה לשבח מכלל דשאר לגנאי:
The bride as she is: And if she has a blemish, they are quiet and they do not praise it. And also (another possibility is) they praise her with something pleasant that she has - for example, [he praises her] about her eyes or her hands if they are beautiful. And Beit Hillel says that you praise her altogether, as when we mention that which she has to be praised, it implies that the rest is negative.
Rav Yehuda says that Shmuel says: With regard to these three matters alone, it is normal for Sages to amend their statements and deviate from the truth: With regard to a tractate, And with regard to a bed, And he can lie with regard to a host [ushpiza], What is the practical difference that emerges from this statement with regard to matters in which Torah scholars deviate from the truth? Mar Zutra says: The practical difference is with regard to returning a lost item on the basis of visual recognition. If we know about him that he alters his statements only with regard to these three matters, we return the lost item to him, but if he alters his statements with regard to other matters, we do not return the lost item to him.
במסכת - יש בידך מסכת פלוני סדורה בגירסא או לאו ואע"ג שסדורה היא לו יאמר לו לאו ומדת ענוה היא:
בפוריא - שימשת מטתך יאמר לאו מדת צניעות הוא:
באושפיזא - שאלוהו על אושפיזו אם קבלו בסבר פנים יפות ואמר לאו מדה טובה היא כדי שלא יקפצו בו בני אדם שאינן מהוגנין לבא תמיד עליו ויכלו את ממונו:
Regarding a tractate- someone asks you, "Do you know tractate so and so very well or not?" Answer him "No." This is the character trait of humility.
Regarding a bed - someone asks you whether you had relations with your spouse. Answer him "No." This is the character of modesty.
Regarding hospitality - If people ask him if his host received him well. Answer them "no." This is a good character trait in order to prevent undesirable guests from inundating him [the host] and exhausting his resources.
Rabbi Eliyahu Dessler, Michtav M’Eliyahu, Vol. I, p. 94
What is truth (אמת) and what is falsehood (שקר)? When we went to school we were taught that truth is to tell facts as they occurred and falsehood is to deviate from this. This is true in simple cases, but in life many occasions arise when this simple definition no longer applies.
Sometimes it may be wrong to “tell the truth” about another person, for example if it would reveal something negative about him, unless there was an overriding purpose and necessity. And sometimes it may be necessary to change details, when the plain truth would not bring benefit, but injury. In such cases what appears to be true is false (שקר), since it produces evil effects; and what appears to be false may help to achieve the truth.
We had better define truth (אמת) as that which is conducive to good and which conforms with the Will of the Creator, and falsehood (שקר) as that which furthers the scheme of the Yetzer HaRah, the power of evil in the world.
And Rabbi Ile’a further said in the name of Rabbi Elazar, son of Rabbi Shimon: It is permitted for a person to depart from the truth in a matter that will bring peace, as it is stated: “Your father commanded before he died, saying: So you shall say to Joseph: Please pardon your brothers’ crime, etc.” (Genesis 50:16–17). Jacob never issued this command, but his sons falsely attributed this statement to him in order to preserve peace between them and Joseph. Rabbi Natan says: It is a mitzva to depart from the truth in order to preserve peace, as it is stated: “And Samuel said: How can I go, and Saul will hear and kill me” (I Samuel 16:2). God responded in the next verse that Samuel should say he went to sacrifice an offering, indicating that God commands one to lie in order to preserve peace. It was taught in the school of Rabbi Yishmael: Great is peace, as even the Holy One, Blessed be He, departed from the truth for it. As, initially it is written that Sarah said of Abraham: “And my lord is old” (Genesis 18:12), and in the end it is written that God told Abraham that Sarah said: “And I am old” (Genesis 18:13). God adjusted Sarah’s words in order to spare Abraham hurt feelings that might lead Abraham and Sarah to quarrel.