Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.005B.

Ibn Majah narrates on the authority of Umar that the Messenger of Allah, peace be upon him, said: “When you visit a sick person, ask him to pray for you. Indeed, the prayer of a sick person is like the prayer of angels.” According to the author of Az-Zawa’ id, the chain of narrators of this hadith is broken, yet it is sound and trustworthy, because otherwise it is authentic and narrators are trustworthy.