Romans 9:18

So then he hath mercy on whom he will, and hardeneth whom he will.

And in them is fulfilled the prophecy of Isaiah, which saith, "Ye will hear indeed, and not understand; and ye will see indeed, and not perceive.

saying, "Go to this people, and say, Hearing ye shall hear, and shall not understand; and seeing ye shall see and not perceive.

Wherefore God also gave them over in the lusts of their hearts to impurity, to debase their bodies with one another;

Moreover the law came in in addition, that the trespass might abound; but where sin abounded, grace abounded much more;

For he saith to Moses, "On whom I have mercy, on him will I have mercy; and on whom I have compassion, on him will I have compassion."

What Israel seeketh after, that Israel did not obtain; but the elect obtained it, and the rest were hardened;

to the praise of the glory of his grace, which he freely bestowed on us in the Beloved;

and in all deceit of unrighteousness for those who are perishing; because they received not the love of the truth, that they might be saved.

Treasury of Scripture Knowledge

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