Musnad Ahmad 26:864

'Affan narrated to us, Shu'bah narrated to us, from Ibrahim al-Hajari, who said: I heard Abu al-Ahwas, from 'Abdullah, from the Prophet (peace and blessings of Allah be upon him), who said: "Do you know which charity is best?" They said: "Allah and His Messenger know best." He said: "The *minihah* (gift/loan of use): that one of you gives his brother a dirham, or the back of a riding animal, or the milk of a sheep, or the milk of a cow."