Musnad Ahmad 28:377

Abu al-Mughirah narrated to us, al-Awza'i narrated to us, from Hassan ibn 'Atiyyah, I heard Abu Kabshah al-Saluli saying: I heard 'Abdullah ibn 'Amr ibn al-'As saying: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Forty good deeds, the highest of which is the lending of a milking goat. There is no servant who performs one of these good deeds, hoping for its reward and believing in its promise, but that Allah will cause him to enter Paradise because of it."