(Those unto whom We gave the Scripture recognise (this revelation) as they recognise their sons…) [2:146]. This was revealed about the believers of the people of the Book: 'Abd Allah ibn Salam and his companions. They knew Allah's Messenger, Allah bless him and give him peace, by his description, traits and mission from their Scripture as did any one of them know his son upon seeing him with other boys. Said 'Abd Allah ibn Salam: “I knew Allah's Messenger, Allah bless him and give him peace, better than I knew my son”. 'Umar ibn al-Khattab asked him: “How is that, O son of Salam?” He said: “Because I bear witness that Muhammad is the Messenger of Allah truly and out of certainty, but I cannot bear witness truly and out of certainty that my son is mine, for I have no knowledge of what women do [behind their husbands' backs]”. 'Umar then said: “May Allah give you success, O son of Salam!”
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou
