Quran 3:90 — The Amramites (Ali-'Imran)

Those who disbelieve after believing, then plunge deeper into disbelief, their repentance will not be accepted from them; they are the real strayers.

[3:89] Exempted are those who repent thereafter, and reform. GOD is Forgiver, Most Merciful.

[3:91] Those who disbelieve and die as disbelievers, an earthful of gold will not be accepted from any of them, even if such a ransom were possible. They have incurred painful retribution; they will have no helpers.