מַתְנִי׳ הַכּוֹתֵב שְׁתֵּי אוֹתִיּוֹת, בֵּין בִּימִינוֹ בֵּין בִּשְׂמֹאלוֹ, בֵּין מִשֵּׁם אֶחָד בֵּין מִשְּׁנֵי שֵׁמוֹת בֵּין מִשְׁתֵּי סַמָּנִיּוֹת, בְּכׇל לָשׁוֹן — חַיָּיב. אָמַר רַבִּי יוֹסֵי: לֹא חִיְּיבוּ שְׁתֵּי אוֹתִיּוֹת אֶלָּא מִשּׁוּם רוֹשֵׁם, שֶׁכָּךְ כּוֹתְבִין עַל קַרְשֵׁי הַמִּשְׁכָּן לֵידַע אֵיזוֹ בֶּן זוּגוֹ. אָמַר רַבִּי יְהוּדָה: מָצִינוּ שֵׁם קָטָן מִשֵּׁם גָּדוֹל — ״שֵׁם״ מִשִּׁמְעוֹן וּמִשְּׁמוּאֵל, ״נֹחַ״ מִנָּחוֹר, ״דָּן״ מִדָּנִיאֵל, ״גָּד״ מִגַּדִּיאֵל.
MISHNA: One who writes two letters on Shabbat, whether he did so with his right hand or his left, whether they were the same letter or two different letters, whether he did so using two different types of ink, in any language, he is liable. Rabbi Yosei said: One is deemed liable for writing two letters only due to marking, as they would write symbols on adjacent beams of the Tabernacle to know which beam was another beam’s counterpart. Rabbi Yehuda said: We found that one is liable for writing even if he did not complete what he was writing, so that he wrote a small name that constituted part of a longer name, e.g., Shem [shin mem] from the name Shimon or from Shmuel; Noaḥ [nun ḥet] from Naḥor; Dan [dalet nun] from Daniel; Gad [gimmel dalet] from Gaddiel. In all of these cases, the first two letters of the longer name constitute the shorter name. GEMARA: The Gemara questions the beginning of the mishna: Granted, for writing with the right hand let one be liable, as that is the typical manner of writing. However, for writing with the left hand, why is one liable? That is not the typical manner of writing. Rabbi Yirmeya said: When the mishna taught that one who writes with his left hand is liable, they taught it with regard to one who is left-handed. The Gemara asks: And if so, let his left hand have the same legal status as everyone’s right hand; for writing with his left hand, let him be liable, for writing with his right hand, let him not be liable. Rather, Abaye said: This mishna refers to an ambidextrous person, who is liable for writing with either hand. Rav Ya’akov, son of the daughter of Ya’akov, said: In accordance with whose opinion is this mishna? It is in accordance with the opinion of Rabbi Yosei, who said: One is deemed liable for writing two letters only due to marking. As such, one is liable for writing a letter even if he writes it imprecisely with his left hand. The Gemara asks: From the fact that the latter clause of the mishna is in accordance with the opinion of Rabbi Yosei, the first clause of the mishna is not in accordance with the opinion of Rabbi Yosei. The Gemara answers: That is not necessarily the case. The entire mishna is in accordance with the opinion of Rabbi Yosei, and the attribution of his second statement was for emphasis alone. We learned in the mishna that Rabbi Yehuda said: We found that one is liable for writing even if he did not complete what he was writing, so that he wrote a small name that constituted part of a longer name. The Gemara asks: Rather, is that to say that according to Rabbi Yehuda, it is one who writes two letters that are two different types of letters who is liable; however, one who writes two letters that are one type of letter is not liable? Wasn’t it taught in a baraita that it is written: “When a leader sinned, and he unwittingly performed one of any of the commandments which the Lord his God commanded not to do, and is guilty” (Leviticus 4:22)? The Sages taught: I might have thought that one is not guilty until he performs a complete labor, e.g., until he writes the entire name that he intended to write, or until he weaves the entire garment, or until he crafts the entire sieve made from the reeds of the warp and the woof; therefore, the verse states: “A soul who sins unintentionally in any of the Lord’s commandments which one shall not perform, and did an action from one of these” (Leviticus 4:2). The emphasis on the phrase “from one” teaches that in order for one to be liable, it is sufficient that he perform only part of the prohibited labor. However, if that is derived from the use of the phrase “from one,” I might have thought that one is liable even if he wrote only a single letter, or even if he wove only a single thread, or even if he crafted only a single eye of the sieve, i.e., arranging the reeds to create a warp, and then interweaving a single reed as a woof;
כָּתַב בְּמַשְׁקִין בְּמֵי פֵּירוֹת, בַּאֲבַק דְּרָכִים בַּאֲבַק הַסּוֹפְרִים וּבְכׇל דָּבָר שֶׁאֵינוֹ מִתְקַיֵּים — פָּטוּר. לְאַחַר יָדוֹ בְּרַגְלוֹ בְּפִיו וּבְמַרְפְּקוֹ, כָּתַב אוֹת אַחַת סָמוּךְ לַכְּתָב, וּכְתָב עַל גַּבֵּי כְּתָב, נִתְכַּוֵּון לִכְתּוֹב חֵי״ת וְכָתַב שְׁתֵּי זַיְינִין, אַחַת בָּאָרֶץ וְאַחַת בַּקּוֹרָה, כָּתַב עַל שְׁנֵי כּוֹתְלֵי הַבַּיִת, עַל שְׁנֵי דַּפֵּי פִנְקָס וְאֵין נֶהֱגִין זֶה עִם זֶה — פָּטוּר. כָּתַב אוֹת אַחַת נוֹטָרִיקוֹן — רַבִּי יְהוֹשֻׁעַ בֶּן בְּתֵירָא מְחַיֵּיב וַחֲכָמִים פּוֹטְרִין.
If one wrote with liquids or with fruit juice, or if one drew letters with road dust, with scribes’ dust that they use to dry the ink, or with any substance with which the writing does not endure, he is exempt. Similarly, if one wrote by holding the pen on the back of his hand, with his foot, with his mouth, or with his elbow; if one wrote only a single letter, even if it was adjacent to other preexisting writing; or if one wrote over other writing; if one meant to write the letter ḥet and instead wrote the two halves of the ḥet as two instances of the letter zayin; if one wrote one letter on the ground and one on a rafter; if one wrote one letter on two walls of a house, or on two parts of a writing tablet that are not read together, he is exempt. If one wrote one letter as an abbreviation representing an entire word, Rabbi Yehoshua ben Beteira deems him liable to bring a sin-offering, and the Rabbis deem him exempt.
אֵין הַכּוֹתֵב חַיָּב עַד שֶׁיִּכְתֹּב בְּדָבָר הָרוֹשֵׁם וְעוֹמֵד כְּגוֹן דְּיוֹ וְשָׁחוֹר וְסִקְרָא וְקוֹמוֹס וְקַנְקַנְתּוֹם וְכַיּוֹצֵא בָּהֶם. וְיִכְתֹּב עַל דָּבָר שֶׁמִּתְקַיֵּם הַכְּתָב עָלָיו כְּגוֹן עוֹר וּקְלָף וּנְיָר וְעֵץ וְכַיּוֹצֵא בָּהֶם. אֲבָל הַכּוֹתֵב בְּדָבָר שֶׁאֵין רִשּׁוּמוֹ עוֹמֵד כְּגוֹן מַשְׁקִין וּמֵי פֵּרוֹת. אוֹ שֶׁכָּתַב בִּדְיוֹ וְכַיּוֹצֵא בּוֹ עַל עֲלֵי יְרָקוֹת וְעַל כָּל דָּבָר שֶׁאֵינוֹ עוֹמֵד פָּטוּר. אֵינוֹ חַיָּב עַד שֶׁיִּכְתֹּב בְּדָבָר הָעוֹמֵד עַל דָּבָר הָעוֹמֵד. וְכֵן אֵין הַמּוֹחֵק חַיָּב עַד שֶׁיִּמְחֹק כְּתָב הָעוֹמֵד מֵעַל דָּבָר הָעוֹמֵד:
A person who writes is not liable until he writes with a substance that leaves a permanent mark - e.g., with ink, black tint, vermilion, gum, vitriol, and the like - on a surface on which the writing will remain preserved - e.g., a skin, parchment, paper, wood, and the like.[In contrast,] a person is not liable if he writes with a substance that does not leave a permanent mark - e.g., beverages or fruit juice - or if he writes with ink and the like on a substance like vegetable leaves where the writing will not be preserved. One is liable only when writing with a substance that leaves a permanent mark on a surface where that mark will be preserved.Similarly with regard to [the forbidden labor of erasing]: A person who erases is liable only when erasing writing that would leave a permanent mark from a surface where that mark will be preserved.
כדי שהמידע יהיה מדויק, צריך לפעמים למחוק אותיות מוטעות על מנת לכתוב במקומן את האותיות הנכונות. גם כשיש בנייר כתם, המוחק אותו כדי לכתוב שם אותיות, עובר על מלאכת מוחק, שבמחיקתו הכשיר את המקום לכתיבה (שו"ע או"ח שמ, ג).
In order to ensure that information is precise, sometimes it is necessary to erase a mistake in order to replace it with accurate information. Even if a piece of paper has a stain on it and one erases it so he can write letters instead, he transgresses Moḥek, as his erasure prepares the writing surface (SA 340:3).
עוגה שכתבו עליה אותיות על ידי קרם או סוכריות קטנטנות וכיוצא בזה, אסור לחותכה במקום האותיות. וכן אם ציירו עליה צורות בעלות משמעות, כמו עץ או בית, אסור לחותכה במקום הצורות. ואף שחיתוך העוגה נעשה לצורך אכילה, כיוון שיש לאותיות ולצורות חשיבות וניכר מאוד שהן נמחקות בעת חיתוך העוגה, יש בזה איסור מדברי חכמים (מרדכי, רמ"א, או"ח שמ, ג). אבל לחתוך בין האותיות מותר, ואף שעל ידי כך מפרידים את המילה לחלקים, אין איסור מחיקה כאשר האותיות נותרות שלימות. לפיכך, הרוצים להכין עוגה כזו לשבת, יכינו אותה באופן שניתן יהיה לחתוך את פרוסותיה בין האותיות והצורות. ואח"כ יהיה מותר לאכול את הפרוסות, למרות שאכילתן תבטל את האותיות, שהואיל ועוסקים באכילה אין זה נחשב 'מוחק'. ובשעת הדחק, כשאין אפשרות אחרת לאכול מהעוגה, מותר לחתוך גם במקום האותיות והצורות.
One may not cut through letters that are written on a cake in frosting, candy, or the like. Similarly, if a cake is decorated with a meaningful picture, like a tree or a house, one may not cut through the picture. Even though one’s intention in cutting the cake is to eat it, since the letters or pictures have meaning and it is very clear that they are being “erased” when the cake is cut, it is rabbinically prohibited (Mordechai; Rema 340:3). However, one may cut between the letters. Even though this separates a word into its component parts, one does not violate Moḥek as long as each letter remains whole. Therefore, if a cake that one plans to serve on Shabbat is being decorated, it should be done in such a way that one will be able to cut between the letters and pictures. Afterward, the slices of cake may be eaten even though eating them will destroy the letters. Since one is engaged in the process of eating, it is not considered Moḥek.