(And when those who believe in Our revelations come unto thee, say: Peace be unto you!) [6:54].
Said 'Ikrimah: “This verse was revealed about those whom Allah, exalted is He, had forbidden His Prophet, Allah bless him and give him peace, from repelling. Whenever the Prophet, Allah bless him and give him peace, saw them, he greeted them first with the greeting of peace, and then said: 'Praise be to Allah Who has made in my community people whom He has commanded me to initiate their greeting with the greeting of peace' ”.
Said Mahan al-Hanafi: “The clan of the Prophet, Allah bless him and give him peace, went to him and said: 'We have committed enormous sins', and I think he answered them with something. When they left, this verse was revealed (And when those who believe in Our revelations come…)”.
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou