I.The extraordinary terror with which the law was given. Never was any thing delivered with such awful pomp; every word was accented, and every sentence paused, with thunder and lightning, much louder and brighter, no doubt, than ordinary. And why was the law given in this dreadful manner, and with all this tremendous ceremony? 1. It was designed (once for all) to give a sensible discovery of the glorious majesty of God, for the assistance of our faith concerning it, that, knowing the terror of the Lord, we may be persuaded to live in his fear. 2. It was a specimen of the terrors of the general judgment, in which sinners will be called to an account for the breach of this law: the archangel's trumpet will then sound an alarm, to give notice of the Judge's coming, and a fire shall devour before him. 3. It was an indication of the terror of those convictions which the law brings into conscience, to prepare the soul for the comforts of the gospel. Thus was the law given by Moses in such a way as might startle, affright, and humble men, that the grace and truth which came by Jesus Christ might be the more welcome. The apostle largely describes this instance of the terror of that dispensation, as a foil to set off our privileges, as Christians, in the light, liberty, and joy, of the New Testament dispensation, Heb 12:18, etc.

II.The impression which this made, for the present, upon the people; they must have had stupid hearts indeed, if this had not affected them. 1. They removed, and stood afar off, Exo 20:18. Before God began to speak, they were thrusting forward to gaze (Exo 19:21); but now they were effectually cured of their presumption, and taught to keep their distance. 2. They entreated that the word should not be so spoken to them any more (Heb 12:19), but begged that God would speak to them by Moses, Exo 20:19. Hereby they obliged themselves to acquiesce in the mediation of Moses, they themselves nominating him as a fit person to deal between them and God, and promising to hearken to him as to God's messenger; hereby also they teach us to acquiesce in that method which Infinite Wisdom takes, of speaking to us by men like ourselves, whose terror shall not make us afraid, nor their hand be heavy upon us. Once God tried the expedient of speaking to the children of men immediately, but it was found that they could not bear it; it rather drove men from God than brought them to him, and, as it proved in the issue, though it terrified them, it did not deter them from idolatry, for soon after this they worshipped the golden calf. Let us therefore rest satisfied with the instructions given us by the scriptures and the ministry; for, if we believe not them, neither should we be persuaded though God should speak to us in thunder and lightning, as he did from Mount Sinai: here that matter was determined.

III.The encouragement Moses gave them, by explaining the design of God in his terror (Exo 20:20): Fear not, that is, "Think not that the thunder and fire are designed to consume you," which was the thing they feared (Exo 20:19, lest we die); thunder and lightning constituted one of the plagues of Egypt, but Moses would not have them think they were sent to them on the same errand on which they were sent to the Egyptians: no, they were intended, 1. To prove them, to try how they would like dealing with God immediately, without a mediator, and so to convince them how admirably well God had chosen for them, in putting Moses into that office. Ever since Adam fled, upon hearing God's voice in the garden, sinful man could not bear either to speak to God or hear from him immediately. 2. To keep them to their duty, and prevent their sinning against God. He encourages them, saying, Fear not, and yet tells them that God thus spoke to them, that his fear might be before their face. We must not fear with amazement - with that fear which has torment, which only works upon the fancy for the present, sets us a trembling, genders to bondage, betrays us to Satan, and alienates us from God; but we must always have in our minds a reverence of God's majesty, a dread of his displeasure, and an obedient regard to his sovereign authority over us: this fear will quicken us to our duty and make us circumspect in our walking. Thus stand in awe, and sin not, Psa 4:4.

IV.The progress of their communion with God by the mediation of Moses, Exo 20:21. While the people continued to stand afar off, conscious of guilt and afraid of God's wrath, Moses drew near unto the thick darkness; he was made to draw near, so the word is: Moses, of himself, durst not have ventured into the thick darkness, if God had not called him, and encouraged him, and, as some of the rabbies suppose, sent an angel to take him by the hand, and lead him up. Thus it is said of the great Mediator, I will cause him to draw near (Jer 30:21), and by him it is that we also are introduced, Eph 3:12.

And all the people saw the thunderings, etc. - They had witnessed all these awful things before, (see Exo 19:16), but here they seem to have been repeated; probably at the end of each command, there was a peal of thunder, a blast of the trumpet, and a gleam of lightning, to impress their hearts the more deeply with a due sense of the Divine Majesty, of the holiness of the law which was now delivered, and of the fearful consequences of disobedience. This had the desired effect; the people were impressed with a deep religious fear and a terror of God's judgments; acknowledged themselves perfectly satisfied with the discoveries God had made of himself; and requested that Moses might be constituted the mediator between God and them, as they were not able to bear these tremendous discoveries of the Divine Majesty. "Speak thou with us, and we will hear; but let not God speak with us, lest we die;" Exo 20:19. This teaches us the absolute necessity of that great Mediator between God and man, Christ Jesus, as no man can come unto the Father but by him.

And Moses said unto the people,.... By representatives and messengers, the heads of the tribes and elders:

fear not; be not afraid of God with a slavish fear; be not afraid of the thunders and lightnings, as if they were like one of the plagues of Egypt, which terrified Pharaoh and his people; be not afraid of being consumed by them, they will do you no hurt; be not afraid of dying by the hand of God, at his presence, and through the voice of his words spoken to you; be of good courage, for the design of God is not to destroy you, but to instruct you, and do you good:

for God is come to prove you; whether, being now freed by him from Egyptian bondage, they would take and own him for their King, and be subject to his laws and government; whether they would abide by what they had said, all that the Lord hath spoken will we do, Exo 19:8, whether they thought they had purity and righteousness enough to answer to the divine law, and whether they imagined they had strength enough to fulfil it, and whether they needed a mediator between God and them or not: some Jewish writers (q) give a different sense of this clause, as if the coming of God to them in this grand and majestic manner was to exalt them, and make them great and honourable among the nations of the world; taking the word used to be derived from a root, which signifies to lift up, as a banner or ensign is lifted up on high: but the former sense is best:

and that his fear may be before your faces; not a slavish fear of death, of wrath, and damnation, before dehorted from; but a reverence of the divine Majesty, an awe of his greatness and glory, a serious regard to his commands, delivered in so grand a manner, and a carefulness to offend him by disobeying them:

that ye sin not: by breaking the law, and transgressing the precepts of it, which they might be deterred from, as it might be reasonably thought, when they reflected with what solemnity, and in what an awful manner it was delivered to them.

(q) Jarchi in loc. Medrash apud Kimchi in Sepher Shorash. rad. & Ben Melech in loc.

all the people saw the thunderings and the lightnings--They were eye and ear witnesses of the awful emblems of the Deity's descent. But they perceived not the Deity Himself.