So then he has mercy on whomever he wills, and he hardens whomever he wills.

What then? Israel failed to obtain what it was seeking. The elect obtained it, but the rest were hardened,

The Mystery of Israel's Salvation

Lest you be wise in your own sight, I do not want you to be unaware of this mystery, brothers: a partial hardening has come upon Israel, until the fullness of the Gentiles has come in.