Musnad Ahmad 1153:1249

Abu Ahmad al-Zubayri narrated to us, Muhammad ibn Sharik narrated to us, from Ibn Abi Mulaykah, from Aisha: That she asked the Prophet, peace and blessings of Allah be upon him, about something regarding the matter of charity, and she mentioned a small amount. The Prophet, peace and blessings of Allah be upon him, said to her: "Give, and do not withhold, lest it be withheld from you."