Psalms 105:43

43.And he brought forth his people with joy The prophet makes mention of joy and gladness, the more highly to magnify the greatness of God’s grace. It was no small matter, that at the very time when the Egyptians were afflicted by a severe and dreadful plague, — when the whole kingdom was full of weeping and howling, — and when in almost every house there was a dead body, — the people who a little before were groaning in great distress, or rather lay almost dead, went forth with joyful hearts. By the appellation the chosen of God, they are reminded, that his favor was not thus exercised towards them on account of their own merits, or on account of the worth of their race, but because he had adopted them, that men having nothing left them in which to vaunt themselves might learn to glory in God alone.