Notes on the Bible, by Albert Barnes, , at sacred-texts.com
Are placed by some with great probability between Exo 24:8-9.
Twelve pillars - As the altar was a symbol of the presence of Yahweh, so these twelve pillars represented the presence of the Twelve tribes with whom He was making the covenant.
Young men of the children of Israel - See Exo 19:22; Exo 28:1; Lev 1:5.
Burnt offerings ... peace offerings - The burnt offerings Lev. 1 figured the dedication of the nation to Yahweh, and the peace offerings Lev. 3 their communion with Yahweh and with each other.
He sprinkled - Rather, he cast. See Lev 1:5.
The book of the covenant - See Exo 20:22 note. The people had to repeat their assent to the book of the covenant before the blood was thrown upon them. Compare Kg2 23:2, Kg2 23:21; Ch2 34:30.
The blood which sealed the covenant was the blood of burnt offerings and peace offerings. The sin-offering Lev. 4 had not yet been instituted. That more complicated view of human nature which gave to the sin-offering its meaning, had yet to be developed by the law, which was now only receiving its ratification. The covenant between Yahweh and His people therefore took precedence of the operation of the law, by which came the knowledge of sin. Rom 3:20.
Upon the people - Either upon the elders or those who stood foremost; or, upon the twelve pillars representing the Twelve tribes, as the first half had been cast upon the altar, which witnessed to the presence of Yahweh. The blood thus divided between the two parties to the covenant signified the sacramental union between the Lord and His people. Cf. Psa 50:5; Zac 9:11.
It would appear that Moses, Aaron with his two sons, and seventy of the elders Exo 19:7 went a short distance up the mountain to eat the meal of the covenant (compare Gen 31:43-47), which must have consisted of the flesh of the peace offerings Exo 24:5. Joshua accompanied Moses as his servant Exo 24:13.
And they saw the God of Israel - As they ate the sacrificial feast, the presence of Yahweh was manifested to them with special distinctness. In the act of solemn worship, they perceived that He was present with them, as their Lord and their Deliverer. It is idle to speculate on the mode of this revelation. That no visible form was presented to their bodily eyes, we are expressly informed, Deu 4:12; see Exo 33:20; compare Isa 6:1. The latter part of this verse may be read: "under His feet, it was like a work of bright sapphire stone, and like the heaven itself in clearness." On the sapphire, see Exo 28:18; compare Eze 1:26. The pure blue of the heaven above them lent its influence to help the inner sense to realize the vision which no mortal eye could behold.
He laid not his hand - i. e. He did not strike them. It was believed that a mortal could not survive the sight of God Exo 33:20; Gen 32:30; Jdg 6:22; Jdg 13:22 : but these rulers of Israel were permitted to eat and drink, while they were enjoying in an extraordinary degree the sense of the divine presence, and received no harm.
Many Jews understand the "tables of stone" to denote the Ten Commandments; "a law," the law written in the Pentateuch; and the "commandments" (or "the commandment"), the oral or traditional law which was in after ages put into writing in the Mishna and the Gemara. But it is more probable that the Ten Commandments alone are spoken of, and that the meaning is, "the tables of stone with the law, even the commandment."
During this period of forty days, and the second period when the tables were renewed, Moses neither ate bread nor drank water. Compare marginal references. In like manner, Elijah fasted for forty days, when he visited the same spot Kg1 19:8. The two who met our Saviour on the Mount of Transfiguration Mat 17:3, the one representing the law, the other representing the Prophets, thus shadowed forth in their own experience the Fast of Forty days in the wilderness of Judaea.