Deuteronomy 27:1

And Moses, with the elders of Israel, commanded the people,
saying
The seventy elders, at the head of whom was Moses, which made the great sanhedrim, or council of the nation; Moses having recited all the laws of God to the people, these joined with him in an exhortation to them to observe and obey them:

keep all the commandments which I command you this day;
not in his own name, as being the supreme legislator, but in the name of the Lord, whom they had avouched to be their God and King, from whom he had received them.