Exodus 24:4

And Moses wrote the words of the Lord — That there might be no mistake; as God dictated them on the mount, where, it is highly probable, God taught him the use of letters. These Moses taught the Israelites, from whom they afterwards travelled to Greece and other nations. As soon as God had separated to himself a peculiar people, he governed them by a written word, as he has done ever since, and will do while the world stands. Pillars according to the number of the tribes — These were to represent the people, the other party to the covenant; and we may suppose they were set up over against the altar, and that Moses as mediator passed to and fro between them. Probably each tribe set up and knew its own pillar, and their elders stood by it. He then appointed sacrifices to be offered upon the altar.