Deuteronomy 2:30

But Sihon, king of Heshbon, would not let us pass by him, through his land; for the Lord, thy God, hardened his spirit, and made his heart obstinate, that He might deliver him into thy hand, as appeareth this day. All obduracy on the part of man is as much a deed of man's freedom, of his own willful transgression, as it is a punishment of God. When man continues to harden his heart to the influence of God, then God, in turn, hardens the sinner until he becomes altogether callous toward all efforts of the Spirit.