Psalms 77:20

Thou leddest thy people like a flock - This may refer to the pillar of cloud and fire. It went before them, and they followed it. So, in the eastern countries, the shepherd does not drape, but leads, his flock. He goes before them to find them pasture, and they regularly follow him.

By the hand of Moses and Aaron - They were God's agents; and acted, in civil and sacred things, just as directed by the Most High.