Hebrews 5:12 in the World English Bible
For although by this time you should be teachers, you again need to have someone teach you the rudiments of the first principles of the revelations of God. You have come to need milk, and not solid food.
Context
11 Of whom we have many things to say, and hard to be uttered, seeing ye are dull of hearing.
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.
13 For every one that useth milk is unskilful in the word of righteousness: for he is a babe.