A.T. Robertson Commentary Hebrews 5:12

"For 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." — Hebrews 5:12 (ASV)

Teachers (διδασκαλο). Predicate nominative after εινα.

By reason of the time (δια τον χρονον). Alas, what a commentary on modern Christians.

That some one teach you the rudiments (του διδασκειν υμας τινα τα στοιχεια). Neat Greek idiom, genitive case of the articular infinitive (need of the teaching) with two accusatives of the person (υμας, you) and the thing (τα στοιχεια, the rudiments) and the accusative of general reference (τινα, as to some one). For στοιχεια see Ga 4:3,9; Colossians 2:8.

Of the first principles of the oracles of God (της αρχης των λογιων του θεου). Three genitives linked to each other. Αρχης (beginning) illustrates τα στοιχεια, just before, the A B C of Christian teaching like Heb 6:1f. Λογιον is a diminutive of logos, divine oracles being usually brief, common in the O.T. and Philo for God's words, in N.T. used for the O.T. (Acts 7:38; Romans 3:2), of God's word through Christians (1 Peter 4:11), of the substance of Christian teaching (Hebrews 5:12).

Of milk (γαλακτος). Because still babes (1 Corinthians 3:2) and not able to chew "solid food" (στερεας τροφης), without intellectual and spiritual teeth.