Wahi is divine revelation exclusive with the Ambiyaa (AS). No human being, besides the Ambiyaa (AS) receives this form of revelation, viz., Wahi.
Wahi is protected by Allah
, hence there is absolutely no possibility of the slightest baatil contaminating it. The Qur'aan Shareef declares emphatically the impossibility of Wahi being contaminated:

“Baatil cannot approach it (Wahi), neither from the front nor from the rear. It is revelation from (Allah) The Wise, The Praiseworthy.”
The connection of the Ambiyaa (AS) with Allah
is thus direct, i.e. through the agency of Wahi which is the medium through which the Deen was communicated. The greatest and most authentic source of Ilm (Knowledge), is Wahi.
Wahi came to the Ambiyaa (AS) in different forms. Sometimes the Wahi was in the form of Speech by Allah
(speaking directly with the Nabi) sometimes through the agency of the Angel Jibraeel (AS) the chief Angel in the transmission of Wahi; sometimes the wahi came in a book, i.e. written; sometimes in the form of a bell ringing; and sometimes in some other forms as well.
The Qur'aan Shareef is the highest product of Wahi bestowed upon man.