Romans 9:15-18

For he says to Moses, “I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion.” It does not, therefore, depend on human desire or effort, but on God’s mercy. For Scripture says to Pharaoh: “I raised you up for this very purpose, that I might display my power in you and that my name might be proclaimed in all the earth.” Therefore God has mercy on whom he wants to have mercy, and he hardens whom he wants to harden.