He mentions the seed of Jacob first, because it had been said to Abraham, For thy seed, and the same promise was repeated to Jacob. (Genesis 26:4; Genesis 28:14) He afterwards adds the seed of David, because an especial promise was afterwards given to David, (2 Samuel 7:12 :) Then also the seed of David, he says, will I reject, that I should not take of his seed to rule over the seed of Abraham, Isaac, and Jacob: he now fitly joins together what might have seemed unconnected; for he says, that there would be always some of David’s posterity to rule over all the tribes. God, therefore, thus preserved his Church when he set a king over his Church; or a kingdom, as we have said, is inseparable from the safety of the people.
He lastly adds, For I will restore their captivity This obviated the diffidence of the people: for an objection was ready at hand, “What can this mean? for the ten tribes have been already led away into distant regions, and are scattered; a part also of the kingdom of Judah has been cut off; and what remains is not far from entire ruin.” Hence God calls their attention to the hope of deliverance, as though he had said, that they were acting foolishly, because they were thus hasty, for their expectation ought to have remained in suspense until the time prescribed, that is, till the end of the seventy years, according to what we have before seen, when the Prophet spoke against impostors who boasted of a quick return. He therefore tells them that they ought patiently to bear their exile, until the full time of their deliverance came. And he points out the fountain or cause of their deliverance when he says, I will have mercy on them, as though he had said, that the very salvation whieh he promised to the people depended on his gratuitous mercy.