"But Allah bears witness to that which He has sent down to you" [Qur'an 4:166], meaning: the Qur'an. "He sent it down with His knowledge, and the angels bear witness" that He sent it down to you. "And sufficient is Allah as a Witness." Muhammad said: The meaning is: And Allah is sufficient as a Witness, and the letter 'ba' (in 'bi-Allah') is for emphasis.