Psalms 77:20 - Albert Barnes' Notes on the Bible

Thou leddest thy people like a flock by the hand of Moses and Aaron - This satisfied and comforted the mind of the psalmist. God had never forsaken his people. He had shown himself faithful in his dealings with them. He had acted the part of a good shepherd. In all the dangers of their way; in their perilous journey through the wilderness; amidst foes, privations, and troubles - rocks, sands, storms, tempests - when surrounded by enemies, and when their camp was infested with poisonous serpents - God had shown himself able to protect his people, and had been faithful to all his promises and covenant-engagements. Looking back to this period of their history, the psalmist saw that there was abundant reason for confiding in God, and that the mind should repose on him calmly amid all that was dark and mysterious in his dealings. In view of the past, the mind ought to be calm; encouraged by the past, however incomprehensible may be God’s doings, people may come to him, and entrust all their interests to him with the confident assurance that their salvation will be secure, and that all which seems dark and mysterious in the dealings of God will yet be made clear.