Hazrat Abu Faakhtah, Sa‘eed bin ‘Ilaaqah (rahimahullah) narrates the following incident:

On one occasion, Hazrat ‘Ali (radhiyallahu ‘anhu) held my hand and said to me, “Let us go and visit Hazrat Hasan (radhiyallahu ‘anhu) as he is sick.” We then proceeded to the house of Hazrat Hasan (radhiyallahu ‘anhu). On arriving at his house, we found that Hazrat Abu Musa (radhiyallahu ‘anhu) had come to visit him.

Hazrat ‘Ali (radhiyallahu ‘anhu) addressed Hazrat Abu Musa (radhiyallahu ‘anhu) asking, “O Abu Musa (radhiyallahu ‘anhu)! With what intention have you come to visit Hazrat Hasan (radhiyallahu ‘anhu)? Have you come to visit him because he is sick, or have you just come to visit him (as the reward for visiting the sick is far greater than meeting your brother at other times)?” Hazrat Abu Musa (radhiyallahu ‘anhu) replied, “I have come to visit him because of his sickness.”

Hazrat ‘Ali (radhiyallahu ‘anhu) then said, “I heard Rasulullah (sallallahu ‘alaihi wasallam) mention, ‘There is no Muslim who visits another Muslim in the morning, on account of his sickness, except that seventy thousand angels make du‘aa for him until the evening, and if he visits him due to his sickness in the evening, seventy thousand angels make du‘aa for him until the morning, and the one visiting a sick person will also receive an orchard in Jannah.”

(Sunan Tirmizi #969)