Musnad Ahmad 281:1

Husayn ibn Muhammad narrated to us, Ibn Abi al-Zinad and Sulayman ibn Dawud narrated to us, they both said: Abd al-Rahman narrated to us, from his father, from Urwah, from Ubayd Allah ibn Abd Allah ibn Utbah, from Ra’itah, the wife of Abd Allah—and she was a skillful woman who used to sell and give charity. She said to Abd Allah one day: "You and your children have kept me busy, so I am unable to give charity along with you." He said: "I would not like for you to do that if there is no reward in it." So they asked the Messenger of Allah, peace and blessings of Allah be upon him, about that. The Messenger of Allah, peace and blessings of Allah be upon him, said to her: "You have the reward for what you spent on them."