Romans 9:18

“Therefore hath he mercy on whom he will, etc..] 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…”

“Therefore hath he--"So then he hath." The result then is that He hath mercy on whom he will have mercy, and whom he will he hardeneth--by judicially abandoning them to the hardening influence of sin itself (Psa 81:11-12; Rom 1:24, Rom 1:26, Rom 1:28; Heb 3:8, Heb 3:13), and of the surrounding incentives to it (Mat 24:12; Co1 15:38; Th2 2:17). Second objection to the doctrine of Divine Sovereignty:”

“Therefore hath he mercy ... - This is a conclusion stated by the apostle as the result of all the argument. Whom he will he hardeneth - This is not stated in what the Scripture said to Pharaoh, but is a conclusion to which the apostle had arrived, in view of the case of Pharaoh. The word “hardeneth” means only to harden in the manner specified in the case of Pharaoh. It does not mean to exert a positive influence, but to leave a sinner to his own course, and to place him in circumstances where the character will be more and more developed; see the note at John 12:40. It implies, however, an act of sovereignty on the part of God in thus leaving him to his chosen course, and in not putting…”

“So then - That is, accordingly he does show mercy on his own terms, namely, on them that believe. And whom he willeth - Namely, them that believe not. He hardeneth - Leaves to the hardness of their hearts. Romans 9:19”

“9:18 he chooses to harden the hearts of others so they refuse to listen: Pharaoh refused to let Israel go because his heart was hardened. God hardened Pharaoh’s heart (Exod 9:12), and Pharaoh hardened his own heart (Exod 8:15).”

“hath: Rom 9:15, Rom 9:16, Rom 5:20, Rom 5:21; Eph 1:6 will he: Rom 1:24-28, Rom 11:7, Rom 11:8; Exo 4:21, Exo 7:13; Deu 2:30; Jos 11:20; Isa 63:17; Mat 13:14, Mat 13:15; Act 28:26-28; Th2 2:10-12 Romans 9:19”