John Calvin Commentary Exodus 24:4

"And Moses wrote all the words of Jehovah, and rose up early in the morning, and builded an altar under the mount, and twelve pillars, according to the twelve tribes of Israel." — Exodus 24:4 (ASV)

And Moses³⁰⁸ wrote all the words of the Lord. This parenthesis is opportunely inserted. For we will see a little further on that the book was read before the people. But, to awaken greater attention, before the reading, he built an altar and offered sacrifices in the sight of all the people.

Moreover, it must be observed that statues³⁰⁹ were erected near the altar according to the number of the tribes. This was so that they would know that they were not kept far away as a sign of rejection. Instead, conscious of their own unworthiness, they were to humble themselves before God in fear and trembling. For although they were removed to a considerable distance, they were still remembered before God. Thus, He embraced them all, as it were, through these statues.

What Moses, however, calls by this name were not images bearing the shape of a man, but heaps of stones. These could serve as monuments representing the twelve tribes, so that they would know they were by no means excluded from the sanctity of the altar.

³⁰⁸ “Had written.” — Lat..

³⁰⁹ “Pillars.” — A V. “Some think that this altar was set upon twelve stones, such as Elias built, 1 Kings 18:31; and Joshua 4:20; in which places, however, the word used is אבנים, (abanim,) which signifieth stones, which were gathered together to make one altar or heap; but here the word is מצבה, (matsebah,) which is a pillar, so called a stando, because it standeth alone, and is erected and set up as a monument.” — Abridged from Willet in loco. See ante, vol. 2, p. 117, and note