Translation:

43. The Unbelievers say: "No apostle art thou." Say: "Enough for a witness between me and you is Allah and such as have knowledge of the Book."

Notes (Tafseer)

1867. The enemies of Islam have to acknowledge that Al-Mustafawas a great and noble character, but they deny his Prophethood. He could point to his credentials from Allah in the work which he achieved, and the Qur-an which he brought.

1868. That is, those who have knowledge of revelation generally will recognise Allah's revelation in the holy Qur-an. An alternative reading is "min 'indi-hi", which is written the same in Arabic, with only three vowel points different. If we adopt that, the last clause will be: "and from Him is (all) knowledge of the Book": i.e., 'as all knowledge of the Book comes from Allah, the Qur-an also bears witness to me'.