Sefer Chasidim Siman 163
Can copy this into an AI, or connect the whole library to your assistant. For deeper learning, you can directly use the original seforim, sites, and apps.
אם נצחת את חבירך אל תשמח מוטב שתהיה מנוצח משתהיה מנצח שהמנצח את חבירו בעולם הזה מוסרים אותו ביד מנוצח לע"ל:
Medieval Jewish mysticism, translated by Sholom Alchanan Singer. Northbrook, Ill. Whitehall Co., 1971
If you defeat your friend, do not rejoice. It is better to be defeated than to be the one who defeats, for one who defeats their friend in this world will be handed over to the defeated one in the World to Come.