Deuteronomy 31:28-30

Gather unto me all the elders It is probable that Moses, having spoken to the people what he was commanded, dismissed them again till he should write the following song; which having done, he summoned the elders (and people, Deu 31:30) to deliver to them from his own mouth what he had written. Moses spake in the ears of all the congregation Pronounced himself, with an audible voice, to the representatives of the congregation, and afterward ordered to be repeated to the people of every tribe, the following song or hymn.