Eruvin 22A

שמשכים ומעריב עליהן לבית המדרש. רבה אמר: במי שמשחיר פניו עליהן כעורב.

who, for the Torah’s sake, gets up early in the morning [shaḥar] and stays late in the evening [erev] in the study hall. Rabba said: In him who, for the Torah’s sake, blackens his face like a raven, i.e., who fasts and deprives himself for the sake of Torah study.

רבא אמר: במי שמשים עצמו אכזרי על בניו ועל בני ביתו כעורב. כי הא דרב אדא בר מתנא הוה קאזיל לבי רב, אמרה ליה דביתהו: ינוקי דידך מאי אעביד להו? אמר לה: מי שלימו קורמי באגמא?

Rava said: In him who makes himself cruel to his sons and other members of his household like a raven for the sake of Torah. This was the case with Rav Adda bar Mattana, who was about to go to the study hall to learn Torah, and his wife said to him: What should I do for your children? How should I feed them in your absence? He said to her: Are all the rushes [kurmei] in the marsh already gone? If there is no other bread, let them eat food prepared from rushes.

״ומשלם לשונאיו אל פניו להאבידו״, אמר רבי יהושע בן לוי: אילמלא מקרא כתוב, אי אפשר לאומרו ⁠— כביכול כאדם שנושא משוי על פניו, ומבקש להשליכו ממנו.

The Talmud proceeds to interpret a different verse homiletically: “And He repays them that hate Him to His face to destroy them; He will not be slack to him that hates Him, He will repay him to his face” (Deuteronomy 7:10). R' Yehoshua ben Levi said: Were the verse not written in this manner, it would be impossible to utter it, in deference to God, for it could be understood, as it were, like a person who bears a burden on his face, and wishes to throw it off. Written slightly differently, the verse could have been understood as implying that God is unable, as it were, to bear the situation, but must punish the wicked immediately.