Musnad Abu Ya'la al-Mawsili 152:53

And from Abdullah, from the Prophet, may Allah bless him and grant him peace, who said: "Do you know which charity is best?" They said: "Allah and His Messenger know best." He said: "The *minhah* (gift/loan), that you grant your brother dinars or dirhams, or a cow, or a sheep, or the back of a riding beast, or the milk of a sheep, or the milk of a cow." And he did not say: "The cow and the sheep."