Hebrews 5:9-12

9and having been made perfect, he became unto all them that obey him the author of eternal salvation; 10named of God a high priest after the order of Melchizedek.

11Of whom we have many things to say, and hard of interpretation, seeing ye are become dull of hearing. 12For when by reason of the time ye ought to be teachers, ye have need again that some one teach you the rudiments of the first principles of the oracles of God; and are become such as have need of milk, and not of solid food.