Shabbat 81B

חסדא: מהו להעלותם אחריו לגג? אמר ליה: גדול כבוד הבריות שדוחה את ״לא תעשה״ שבתורה. יתיב מרימר וקאמר לה להא שמעתא. איתיביה רבינא למרימר: רבי אליעזר אומר נוטל אדם קיסם משלפניו לחצות בו שיניו, וחכמים אומרים לא יטול אלא מן האבוס של בהמה! הכי השתא?! התם ⁠— אדם קובע מקום לסעודה, הכא ⁠— אדם קובע מקום לבית הכסא?

Ḥisda: What is the halakha with regard to taking those stones up with him to the roof if his latrine is there? Is it permitted or is it prohibited due to the exertion involved? He said to him: It is permitted; great is human dignity as it overrides a prohibition in the Torah. The Talmud relates: Mareimar sat and stated this halakha. Ravina raised an objection to the statement of Mareimar from a baraita where R' Eliezer says: A person may take a wood chip from the ground before him to clean his teeth on Shabbat. And the Rabbis say one may take a wood chip only from the animal’s trough, which is already designated for the animal’s use, but not from wood on the ground, which is set-aside. Apparently, despite the fact that using the wood chip enhances human dignity, it is nevertheless prohibited due to the prohibition of set-aside. The Talmud rejects this: How can you compare? There, a person determines the place for his meal. Since he knows where he will eat he should have prepared toothpicks beforehand. Here, does a person determine the place for a latrine? He relieves himself wherever he finds a discreet place to do so.

אמר רב הונא: אסור לפנות בשדה ניר בשבת. מאי טעמא? אילימא משום דוושא ⁠— אפילו בחול נמי! ואלא משום עשבים, והאמר ריש לקיש: צרור שעלו בו עשבים ⁠— מותר לקנח בו. והתולש ממנה בשבת ⁠— חייב חטאת. אלא דילמא נקיט מעילאי ושדי לתתאי, ומיחייב משום דרבה. דאמר רבה: היתה לו גומא וטממה, בבית ⁠— חייב משום בונה, בשדה ⁠— חייב משום חורש.

Rav Huna said: It is prohibited to defecate in a plowed field on Shabbat. The Talmud asks: What is the reason for that prohibition? If you say it is due to the fact that in doing so he treads on the furrows and destroys them, it should be prohibited even on weekdays. Rather, it is due to the concern that he will clean himself with a clod of earth on which grasses have grown. Didn’t Reish Lakish say that it is permitted to wipe with a stone upon which grasses have grown even though the grasses will be detached as a result? And that is the halakha even though one who unwittingly detaches grasses from it on Shabbat is liable to bring a sin-offering. Rather, the concern is lest he take a clod of earth from a high place, a pile of dirt, and throw it to a low place, into a hole in the ground. And in that case, he would be liable due to that which Rabba said, as Rabba said: If one had a hole and filled it, in the house, he is liable due to the prohibited labor of building; in the field, he is liable due to plowing.