And just as among those who outwardly profess Islam there are people who, in appearance, are genuine Muslims, while others are hypocrites—disbelievers at heart who may in fact be Jews, Christians, idol-worshippers, or deniers of God’s attributes—
so it is with the People of the Book and the polytheists: some of them do outwardly belong to their communities, yet inwardly they are believers in Muhammad—may Allah bless him and grant him peace. Such a person does whatever knowledge and practice he is capable of, and whatever lies beyond his capacity is waived for him.

Hammad ibn Salamah relates, through Thabit, from Anas that he said:
“When the Negus died, the Prophet—may Allah bless him and grant him peace—said, ‘Ask forgiveness for your brother.’ Some of the people objected, saying, ‘You are telling us to seek forgiveness for this foreigner who has died in Abyssinia?’ Thereupon the verse was revealed:
‘Indeed, among the People of the Book are those who believe in Allah, in what was sent down to you, and in what was sent down to them’ [Āl ʿImrān: 199].”