Hebrews 5:12; Hebrews 8:11

12 For when for the time ye ought to be teachers, ye have need that one teach you again which be the first principles of the oracles of God; and are become such as have need of milk, and not of strong meat.
11 And they shall not teach every man his neighbour, and every man his brother, saying , Know the Lord: for all shall know me, from the least to the greatest .