Sahih Muslim
The Book of Virtue, Good Manners and Joining of the Ties of Relationship (Kitab Al-Birr was-Salat-I-wal-Adab)
Book Number: 032 / Hadith Number: 6228
Thauban, the freed slave of Allah's Messenger (may peace be upon him), reported that Allah's Messenger (may peace be upon him) said: He who visits the sick continues to remain in the fruit garden of Paradise until he returns.