Romans 9:18

Therefore hath he mercy on whom he will have mercy, and whom he will he hardeneth.

Therefore hath he mercy on whom he will,.... These are the express words of the former testimony: it follows,

and whom he will he hardeneth; which is the just and natural consequence of what is contained in the latter; for if God could, or he did, without any injustice, raise up Pharaoh, and harden his heart against him and his people, that he might rise up against him and destroy him by his power for his own glory, then he may harden any other person, and even whom he will: now this hardening of men's hearts may be understood in perfect agreement with the justice and holiness of God: men first harden their own hearts by sinning, as Pharaoh did; what God does, is by leaving them to the hardness of their hearts, denying them that grace which only can soften them, and which he is not obliged to give, and therefore does them no injustice in withholding it from them; by sending them both mercies and judgments, which through the corruption of their hearts, are the means of the greater hardening of them; so judgments in the case of Pharaoh, and mercies in the case of others; see Isaiah 6:10; by delivering them up into the hands of Satan, and to their own lusts, which they themselves approve of; and by giving them up to a judicial blindness and hardness of heart, as a just punishment for their impieties.