Volume 4 · Book 53 · Hadith 357
Narrated Anas bin Malik: People used to give some of their datepalms to the Prophet (as a gift), till he conquered Bani Quraiza and Bani AnNadir, whereupon he started returning their favors.
— Sahih Bukhari, Volume 4, Book 53: One-fifth of Booty to the Cause of Allah (Khumus), Hadith #357