Deuteronomy 18:17

I will raise them up a prophet from among their brethren like unto thee,.... So that it seems this promise or prophecy was first made at Mount Sinai, but now renewed and repeated, and which is nowhere else recorded; see Deu 18:15 when they were not only made easy for the present by appointing Moses to receive from the Lord all further notices of his mind and will, but were assured that when it was his pleasure to make a new revelation, or a further discovery of his mind and will, in future times, he would not do it in that terrible way he had delivered the law to them; but would raise up a person of their own flesh and blood, by whom it should be delivered, which was sufficient to prevent their fears for the future:

and will put my word in his mouth; the doctrines of the Gospel, which come from God, and are the words of truth, faith, righteousness, peace, pardon, life, and salvation; and which Christ says were not his own, as man and Mediator, but his Father's, which he gave unto him, and put into his mouth, as what he should say, teach, and deliver to others; see Joh 7:16.