“They trembled and stood afar off:” not daring to come nearer to the mountain, or to ascend it. “And they said,” viz., the heads of the tribes and elders: cf. Deu 5:20, where the words of the people are more fully given. “Lest we die:” cf. Deu 5:21-23. Though they had discovered that God speaks with man, and yet man lives; they felt so much that they were בּשׂר, flesh, i.e., powerless, frail, and alienated by sin from the holy God, that they were afraid lest they should be consumed by this great fire, if they listened any longer to the voice of God.
Verse 20
To direct the sinner's holy awe in the presence of the holy God, which was expressed in these words of the people, into the proper course of healthy and enduring penitence, Moses first of all took away the false fear of death by the encouraging answer, “Fear not,” and then immediately added, “for God is come to prove you.” נסּוּת referred to the testing of the state of the heart in relation to God, as it is explained in the exegetical clause which follows: “that His fear may be before your faces, that ye sin not.” By this terrible display of His glory, God desired to inspire them with the true fear of Himself, that they might not sin through distrust, disobedience, or resistance to His guidance and commands.
Verse 21
“So the people stood afar off” (as in Exo 20:18), not “went far away,” although, according to Deu 5:30, Moses was directed by God to tell the people to return to their tents. This is passed over here, and it is merely observed, for the purpose of closing the first act in the giving the law, and preparing the way for the second, that the people remained afar off, whereas Moses (and Aaron, cf. Exo 19:24) drew near to the darkness where God was, to receive the further commands of the Lord.
