Adam Clarke on Romans 9:17

For the Scripture saith unto Pharaoh - Instead of showing the Israelites mercy he might justly have suffered them to have gone on in sin, till he should have signalized his wisdom and justice in their destruction; as appears from what God in his word declares concerning his dealings with Pharaoh and the Egyptians, Exo 9:15, Exo 9:16 : For now, saith the Lord, I had stretched forth my hand, (in the plague of boils and blains), and I had smitten thee and thy people with the pestilence; and thou hadst (by this plague) been cut off from the earth; (as thy cattle were by the murrain); but in very deed for this cause have I raised thee up - I have restored thee to health by removing the boils and blains, and by respiting thy deserved destruction to a longer day, that I may, in thy instance, give such a demonstration of my power in thy final overthrow, that all mankind may learn that I am God, the righteous Judge of all the earth, the avenger of wickedness. See this translation of the original vindicated in my notes on Exo 9:15 (note), Exo 9:16 (note); and, about the hardening of Pharaoh, see the notes on those places where the words occur in the same book.