Musnad Ahmad 5:140

Ubaydah ibn Humayd narrated to us, Thuwayr ibn Abi Fakhitah narrated to me, from his father, who said: Abu Musa al-Ash’ari visited al-Hasan ibn Ali. He said: Ali entered upon me and said: "Have you come as a visitor of the sick, O Abu Musa, or as a guest?" He said: "O Commander of the Faithful, nay, but as a visitor of the sick." Ali said: "For I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'No Muslim visits a Muslim [who is sick] except that seventy thousand angels pray for him from the time he reaches the morning until he reaches the evening, and Allah the Exalted appoints for him a *kharif* in Paradise.'" He said: We said: "O Commander of the Faithful, and what is the *kharif*?" He said: "The canal that waters the palm trees."