Exodus 24:2-4 New International Version - UK (NIVUK)
2 but Moses alone is to approach the Lord; the others must not come near. And the people may not come up with him.’
3 When Moses went and told the people all the Lord’s words and laws, they responded with one voice, ‘Everything the Lord has said we will do.’ 4 Moses then wrote down everything the Lord had said.
He got up early the next morning and built an altar at the foot of the mountain and set up twelve stone pillars representing the twelve tribes of Israel.