Charles Ellicott Commentary Romans 9:18

"So then he hath mercy on whom he will, and whom he will be hardeneth." — Romans 9:18 (ASV)

Summary conclusion from the above.

He hardeneth.—The doctrine of divine sovereignty is expressed here in its most trenchant and logical form. In Exodus 8:32; Exodus 9:34; Exodus 13:15, and so on, the hardening of Pharaoh’s heart is attributed to his own act. That act may, however, be regarded as a part of the design of Providence. God’s decrees include human free will, without destroying it. But how they do this we cannot say.