(But Allah (Himself) testifieth concerning that which He hath revealeth unto thee…) [4:166].
Said al-Kalbi: “The leaders of Mecca went to the Messenger of Allah, Allah bless him and give him peace, and said to him: ‘We have asked the Jews about you and they claimed they do not know you. Therefore, bring us somebody who would testify to us that Allah has sent you to us as a messenger’, and so this verse was revealed”.
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou