Musnad Ahmad 33:148

Hushaym narrated to us, from ‘Abd al-Hamid ibn Ja‘far, from ‘Umar ibn al-Hakam ibn Thawban, from Jabir ibn ‘Abd Allah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever visits a sick person continues to wade in mercy until he sits down. So when he sits, he is immersed in it."