Musnad Ahmad 1156:199

Hammad ibn Usamah narrated to us, he said: Hisham narrated to us, from his father, from Zaynab bint Abi Salamah, from Umm Salamah, who said: I said: "O Messenger of Allah, is there a reward for me regarding the sons of Abu Salamah if I spend upon them? And I am not going to leave them like this and like that; they are only my sons." He said: "Yes, you have a reward in them for what you spend upon them."