A.T. Robertson Commentary Hebrews 12:20

"for they could not endure that which was enjoined, If even a beast touch the mountain, it shall be stoned;" — Hebrews 12:20 (ASV)

For they could not endure (ουκ εφερον γαρ). Imperfect active of φερω, "for they were not enduring (bearing)."

That which was enjoined (το διαστελλομενον). Present passive articular participle of διαστελλω, old verb to distinguish, to dispose, to order. The quotation is from Ex 19:12f. The people appealed to Moses (Exodus 20:19) and the leaders did so also (Deuteronomy 5:23f.), both in terror.

If even (καν). "Even if." Condition of third class with second aorist active subjunctive of θιγγανω as in 11:28, followed by genitive ορους (mountain).

It shall be stoned (λιθοβοληθησετα). From Ex 19:13. Late compound verb from λιθοβολος (from λιθοσ, βαλλω) as in Mt 21:35.