Charles H. Spurgeon on Psalms 77:20

By the hand of Moses and Aaron. He says not, Moses and Aaron led the people of Israel; but, Thou leddest the people, and that thy people, by the hand of Moses and Aaron. Great was the power of these two men; nevertheless neither of them was the shepherd of the sheep, but each was a servant to the one and only true shepherd, to whom the sheep exclusively belonged. Nor yet was either the leader of the sheep, but the shepherd himself was present and led his own flock, to whom these two acted as servants. There are therefore three things to be learned from this passage. First, the sheep do not belong to the servants, but to the true shepherd. Secondly, the true shepherd is the leader of his own sheep. Thirdly, the offices of Moses and Aaron was to attend to this duty, that the Lord's sheep should be properly led and pastured. So Christ himself leads the sheep, his own sheep, and for this work he employs the ministry of his servants. Musculus.