Therefore hath he mercy on whom he will have mercy, and whom he will he hardeneth.
Ver. 18. Therefore] God being a free agent, cannot be unjust; he is bound to none.
Whom he will, he hardeneth] There is a threefold hardness of the heart: 1. Natural and hereditary, whereby all men are by nature not only averse from, but also adverse to, the motions of grace; this is called a neck possessed with an iron sinew, Isaiah 48:4; Isaiah 2:1,22. Actual, adventitious, voluntary; which is, when, by often choking good motions, a man hath quit his heart of them; being arrived at that dead and dedolent disposition, Ephesians 4:18, past feeling, and ripe for destruction. This is called a brow of brass in the above named text, Isaiah 48:4; Isaiah 3:1,26. Judiciary, penal hardness; happens when God, for a punishment of the former, withholds his graces, and delivers a man up to Satan to be further hardened, and to his own heart's lusts, which is worse. The incestuous person was delivered up to Satan, and yet repented; but he that is delivered up to his own heart, to a reprobate mind, cannot be renewed by repentance; but is in the ready road to that unpardonable sin. And this last is here meant.