Angels

Say, “The Holy Spirit has brought it down from your Lord with truth, to strengthen the believers and as guidance and good news for those who submit.”

16:102Say: The holy Spirit hath delivered it from thy Lord with truth, that it may confirm (the faith of) those who believe, and as guidance and good tidings for those who have surrendered (to Allah).

Say, 'Whoever opposes Gabriel should know that he brings revelation by Allah’s command.

2:97Say (O Muhammad, to mankind): Who is an enemy to Gabriel! For he it is who hath revealed (this Scripture) to thy heart by Allah's leave, confirming that which was (revealed) before it, and a guidance and glad tidings to believers;

Carried by scribes.

80:15(Set down) by scribes

He sent it down with full knowledge, and the angels also testify.

4:166But Allah (Himself) testifieth concerning that which He hath revealeth unto thee; in His knowledge hath He revealed it; and the angels also testify. And Allah is sufficient Witness.