Here, I. God intimates to Moses his purpose of coming down upon Mount Sinai, in some visible appearance of his glory, in a thick cloud (v. 9); for he said that he would dwell in the thick darkness (2 Chron. vi. 1), and make this his pavilion (Ps. xviii. 11), holding back the face of his throne when he set it upon Mount Sinai, and spreading a cloud upon it, Job xxvi. 9. This thick cloud was to prohibit curious enquiries into things secret, and to command an awful adoration of that which was revealed. God would come down in the sight of all the people (v. 11); though they should see no manner of similitude, yet they should see so much as would convince them that God was among them of a truth. And so high was the top of Mount Sinai that it is supposed that not only the camp of Israel, but even the countries about, might discern some extraordinary appearance of glory upon it, which would strike a terror upon them. It seems also to have been particularly intended to put an honour upon Moses: That they may hear when I speak with thee, and believe thee for ever, v. 9. Thus the correspondence was to be first settled by a sensible appearance of the divine glory, which was afterwards to be carried on more silently by the ministry of Moses. In like manner, the Holy Ghost descended visibly upon Christ at his baptism, and all that were present heard God speak to him (Matt. iii. 17), that afterwards, without the repetition of such visible tokens, they might believe him. So likewise the Spirit descended in cloven tongues upon the apostles (Acts ii. 3), that they might be believed. Observe, When the people had declared themselves willing to obey the voice of God, then God promised they should hear his voice; for, if any man be resolved to do his will, he shall know it, John vii. 17.
II. He orders Moses to make preparation for this great solemnity, giving him two days' time for it.
1. He must sanctify the people (v. 10), as Job, before this, sent and sanctified his sons, Job i. 5. He must raise their expectation by giving them notice what God would do, and assist their preparation by directing them what they must do. "Sanctify them," that is, "Call them off from their worldly business, and call them to religious exercises, meditation and prayer, that they may receive the law from God's mouth with reverence and devotion. Let them be ready," v. 11. Note, When we are to attend upon God in solemn ordinances it concerns us to sanctify ourselves, and to get ready beforehand. Wandering thoughts must be gathered in, impure affections abandoned, disquieting passions suppressed, nay, and all cares about secular business, for the present, dismissed and laid by, that our hearts may be engaged to approach unto God. Two things particularly prescribed as signs and instances of their preparation:--(1.) In token of their cleansing themselves from all sinful pollutions, that they might be holy to God, they must wash their clothes (v. 10), and they did so (v. 14); not that God regards our clothes; but while they were washing their clothes he would have them think of washing their souls by repentance from the sins they had contracted in Egypt and since their deliverance. It becomes us to appear in clean clothes when we wait upon great men; so clean hearts are required in our attendance on the great God, who sees them as plainly as men see our clothes. This is absolutely necessary to our acceptably worshipping God. See Ps. xxvi. 6; Isa. i. 16-18; Heb. x. 22. (2.) In token of their devoting themselves entirely to religious exercises, upon this occasion, they must abstain even from lawful enjoyments during these three days, and not come at their wives, v. 15. See 1 Cor. vii. 5.
2. He must set bounds about the mountain, v. 12, 13. Probably he drew a line, or ditch, round at the foot of the hill, which none were to pass upon pain of death. This was to intimate, (1.) That humble awful reverence which ought to possess the minds of all those that worship God. We are mean creatures before a great Creator, vile sinners before a holy righteous Judge; and therefore a godly fear and shame well become us, Heb. xii. 28; Ps. ii. 11. (2.) The distance at which worshippers were kept, under that dispensation, which we ought to take notice of, that we may the more value our privilege under the gospel, having boldness to enter into the holiest by the blood of Jesus, Heb. x. 19.
3. He must order the people to attend upon the summons that should be given (v. 13): "When the trumpet soundeth long then let them take their places at the foot of the mount, and so sit down at God's feet," as it is explained, Deut. xxxiii. 3. Never was so great a congregation called together, and preached to, at once, as this was here. No one man's voice could have reached so many, but the voice of God did.
The Divine Presence on Mount Sinai. (b. c. 1491.)