Romans 9:15-18

For he tells Moses, I will show mercy to whom I will show mercy, and I will have compassion on whom I will have compassion. So then, it does not depend on human will or effort but on God who shows mercy. For the Scripture tells Pharaoh, I raised you up for this reason so that I may display my power in you and that my name may be proclaimed in the whole earth. So then, he has mercy on whom he wants to have mercy and he hardens whom he wants to harden.