Sahih Muslim Book 5, Hadith Number 2236.

Chapter : Concerning the collection of Sadaqa and doing of good deeds.

Umair, the freed slave of Abi’l-Lahm reported: I was the slave (of Abi’l-Lahm). I asked the Messenger of Allah (may peace be upon him) if I could give some charity out of my master’s wealth. He said: Yes, and the reward is half and half between you two.