He sent Moses his servant Here the prophet briefly adverts to such things regarding the deliverance of the people as were worthy of particular notice. Had the Egyptians of their own accord suffered the people to depart, neither the service of Moses nor miracles would have been required. God then appointed that their deliverance should take place in such a way, as would render the denial of his being its author impossible. Moses is called the servant of the Lord, to teach us that he was not self-elected to his office, and that he attempted nothing by his own authority, but, being the minister of God, executed the office with which he had been intrusted. The same thing is expressed still more plainly with respect to Aaron, when he is said to have been chosen What is attributed to each of these eminent men in particular, applies equally to both, and therefore the sentence ought to be explained thus: God sent Moses and Aaron, his servants, not because of their own intrinsic fitness, or because they spontaneously offered to him their service, but because he chose them. This passage teaches us, that those who are engaged in active and useful service for the Church, are not prepared exclusively by their own exertions, or framed to it by their own talents, but are stirred up thereto by God. Moses was a man of heroic virtue: but, considered merely in himself, he was nothing. Accordingly, the prophet would have all that is accounted worthy of remembrance in Moses, as well as in Aaron, to be ascribed to God alone. Thus it appears that whatever men do for the welfare of the Church, they owe the power of doing it to God, who, of his free goodness, has been pleased thus to honor them.

He sent Moses his servant - He sent Moses to be his servant in delivering his people; that is, to accomplish the work which he had designed should be done.
And Aaron whom he had chosen - whom he had selected to perform an important work in delivering his people from bondage.

He sent Moses his servant,.... Into Egypt, to deliver his people Israel out of the hands of the Egyptians; in which, as in other things, he approved himself to be a faithful servant to the Lord; of this mission of his, see Exodus 3:10. In this he was a type of Christ, who appeared in the form of a servant, and really was one; God's righteous servant as Mediator, though his Son as a divine Person; sent by him to redeem his people out of worse than Egyptian bondage, from sin, Satan, the law, its curse and condemnation.
And Aaron whom he had chosen; to go along with Moses, to be a mouth for him, and a prophet to him, Exodus 4:16, who also was a type of Christ, being a priest and good spokesman, chosen and called of God, a holy and an anointed one. The Targum is,
"in whom he was well pleased.''

Moses . . . chosen--both what they were by divine choice (Psalm 78:70).