Musnad Ahmad 31:278

Waki' narrated to us, Ibn Abi Layla narrated to us, from 'Atiyyah, from Abu Sa'id, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "Charity is not lawful for a wealthy person, except for three: one in the way of Allah, a wayfarer, and a man who had a neighbor, so he gave him charity, and he (the neighbor) gifted it to him."