(48) باب الزَّكَاةِ عَلَى الزَّوْجِ وَالأَيْتَامِ فِي الْحَجْرِ
Narrated Zainab:
(the daughter of Um Salama) My mother said, "O Allah's Messenger (ﷺ)! Shall I receive a reward if I spend for the sustenance of Abu Salama's offspring, and in fact they are also my sons?" The Prophet (ﷺ) replied, "Spend on them and you will get a reward for what you spend on them."
Reference: Sahih al-Bukhari 1467
In-book reference: Book 24, Hadith 70
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 24, Hadith 546