Romans 9:15-16

9:15 For he says to Moses: “I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion.” 9:16 So then, it does not depend on human desire or exertion, but on God who shows mercy.

Romans 9:18

9:18 So then, God has mercy on whom he chooses to have mercy, and he hardens whom he chooses to harden.