אִם־רָעֵ֣ב שֹׂ֭נַאֲךָ הַאֲכִלֵ֣הוּ לָ֑חֶם וְאִם־צָ֝מֵ֗א הַשְׁקֵ֥הוּ מָֽיִם׃
אַז דײַן שׂונא איז הונגעריק, גיב אים עסן ברױט, און אַז ער איז דאָרשטיק, גיב אים טרינקען װאַסער;
Sefer Chasidim
The scholar said, “Give good and upright advice to all men who come to you to be advised, even your enemies.” For two reasons, firstly, because of heavenly law, that there be no sin in you. Secondly, in this way you will exact revenge from your enemies. Inasmuch that your enemy thinks in his heart, “Surely this man hates me and did not advise me well,” he will turn aside from your thoughts and do something else which will be to his detriment.1Proverbs 25:21-22.