And Moses brought forth the people out of the camp to meet with God; and they stood at the nether part of the mount. And Moses brought forth the people - to meet with God - For though they might not touch the mount till they had permission, yet when the trumpet sounded long, it appears they might come up to the nether part of the mount, (see Exodus 19:13, and Deuteronomy 4:11); and when the trumpet had ceased to sound, they might then go up unto the mountain, as to any other place.
It was absolutely necessary that God should give the people at large some particular evidence of his being and power, that they might be saved from idolatry, to which they were most deplorably prone; and that they might the more readily credit Moses, who was to be the constant mediator between God and them. God, therefore, in his indescribable majesty, descended on the mount; and, by the thick dark cloud, the violent thunders, the vivid lightnings, the long and loud blasts of the trumpet, the smoke encompassing the whole mountain, and the excessive earthquake, proclaimed his power, his glory, and his holiness; so that the people, however unfaithful and disobedient afterwards, never once doubted the Divine interference, or suspected Moses of any cheat or imposture. Indeed, so absolute and unequivocal were the proofs of supernatural agency, that it was impossible these appearances could be attributed to any cause but the unlimited power of the author of Nature.
It is worthy of remark that the people were informed three days before, Exodus 19:9-11, that such an appearance was to take place; and this answered two excellent purposes:
1. They had time to sanctify and prepare themselves for this solemn transaction; and,
2. Those who might be skeptical had sufficient opportunity to make use of every precaution to prevent and detect an imposture; so this previous warning strongly serves the cause of Divine revelation.
Their being at first prohibited from touching the mount on the most awful penalties, and secondly, being permitted to see manifestations of the Divine majesty, and hear the words of God, subserved the same great purposes. Their being prohibited in the first instance would naturally whet their curiosity, make them cautious of being deceived, and ultimately impress them with a due sense of God's justice and their own sinfulness; and their being permitted afterwards to go up to the mount, must have deepened the conviction that all was fair and real, that there could be no imposture in the case, and that though the justice and purity of God forbade them to draw nigh for a time, yet his mercy, which had prescribed the means of purification, had permitted an access to his presence. The directions given from Exodus 19:10-15 inclusive show, not only the holiness of God, but the purity he requires in his worshippers.
Besides, the whole scope and design of the chapter prove that no soul can possibly approach this holy and terrible Being but through a mediator; and this is the use made of this whole transaction by the author of the Epistle to the Hebrews, Hebrews 12:18-24.