Musnad Ahmad 5:391

Bahz and ‘Affan narrated to us, they said: Hammad ibn Salamah narrated to us, from Ya‘la ibn ‘Ata’, who said—‘Affan said: Ya‘la ibn ‘Ata’ informed us—from ‘Abdullah ibn Yasar, from ‘Amr ibn Hurayth, that he visited Hasan [to inquire after his health], and ‘Ali was with him. ‘Ali said: "Do you visit Hasan while there is what there is in the soul [regarding him]?" He said: "Yes, for you are not the Lord of my heart so that you may turn it wherever you wish." He [‘Ali] said: "As for that, it does not prevent me from offering you sincere advice. I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'There is no Muslim who visits a Muslim [to inquire after his health] except that Allah sends forth for him seventy thousand angels who invoke blessings upon him at whatever hour of the day it may be until he reaches evening, and at whatever hour of the night it may be until he reaches morning.'"