Musannaf Ibn Abi Shayba 5:13

Waki’ narrated to us, from ‘Abbad ibn Mansur, from al-Qasim ibn Muhammad, who said: I heard Abu Hurayrah, from the Prophet (may Allah bless him and grant him peace), saying: "Indeed, Allah accepts charity and takes it with His right hand, then He nurtures it for its owner just as one of you nurtures his foal or his young camel, until the morsel becomes like Mount Uhud." And the confirmation of that is in the Book of Allah, the Almighty and Majestic: "And it is He who accepts repentance from His servants and takes the charities," and: "Allah destroys interest and nurtures charities."