Musnad Ahmad 35:7

Muhammad ibn Ubayd narrated to us, from Amr ibn Uthman, from Musa ibn Talhah, from Hakim ibn Hizam, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "Indeed, the best of charity is that which is given out of surplus wealth, and the upper hand is better than the lower hand, and begin with those whom you support."