In Romans 9:18 it says that God hardens whom He will (but only after man has hardened himself, as the example of Pharaoh shows (v.14-17).
Katika Waroma 9,18 tunasoma ya kuwa Mungu anafanya mgumu atakaye (ila nyuma mtu ajifanya mgumu mwenyewe, kama tuonapo mfano wa Farao: Waroma 9,14-17).