Musnad Ahmad 55:1

Muhammad ibn Abi ‘Adi narrated to us, from Humayd, from a man from the people of Makkah who was called Yusuf, he said: I and a man from Quraysh were in charge of the wealth of orphans. He said: A man had taken a thousand dirhams from me. He said: Then a thousand dirhams of his fell into my hands. He said: So I said to the Qurayshi, "He has taken a thousand dirhams from me, and I have obtained a thousand dirhams of his." He said: The Qurayshi said: My father narrated to me that he heard the Messenger of Allah (peace and blessings of Allah be upon him) saying: "Render the trust to the one who entrusted you, and do not betray the one who betrayed you."