Verse 12. - On this occasion the people heard the voice of the words, but saw no similitude; there was no form or shape apparent to the eye. No man can see God's face (Exodus 33:20, 23); "no man hath seen God at any time" (John 1:18); and though the nobles or elders of Israel who went up with Moses into the mount are said to have seen God, it is evident that what they saw was only some luminous manifestation of his glory, and not a form or shape of which a similitude could be made (Exodus 24:9-17). Even Moses, with whom God said that he would speak mouth to month, and who should behold the similitude of God (Numbers 12:8), was told that he could not see his face, his essential personality, but only his back, the reflection of his glory (Exodus 33:18-23).

4:1-23 The power and love of God to Israel are here made the ground and reason of a number of cautions and serious warnings; and although there is much reference to their national covenant, yet all may be applied to those who live under the gospel. What are laws made for but to be observed and obeyed? Our obedience as individuals cannot merit salvation; but it is the only evidence that we are partakers of the gift of God, which is eternal life through Jesus Christ, Considering how many temptations we are compassed with, and what corrupt desires we have in our bosoms, we have great need to keep our hearts with all diligence. Those cannot walk aright, who walk carelessly. Moses charges particularly to take heed of the sin of idolatry. He shows how weak the temptation would be to those who thought aright; for these pretended gods, the sun, moon, and stars, were only blessings which the Lord their God had imparted to all nations. It is absurd to worship them; shall we serve those that were made to serve us? Take heed lest ye forget the covenant of the Lord your God. We must take heed lest at any time we forget our religion. Care, caution, and watchfulness, are helps against a bad memory.And the Lord spake unto you out of the midst of the fire,.... For the Lord descended on Mount Sinai in a cloud, in fire, and was in the thick darkness, from whence he delivered out the ten commands:

ye heard the voice of the words; distinctly and plainly, not only the sound of them, but the words themselves, and so as to understand what was meant by them:

but saw no similitude; not any likeness of the person speaking, by which they could form any idea of him in their minds, which was purposely done to prevent idolatry:

only ye heard a voice; that was all.