repentance
Feminine verbal noun (maṣdar) of تَابَ. The root ت-و-ب means 'to return/turn back.' God is التَّوَّابُ (The Oft-Returning, The Acceptor of Repentance).
Tawbah in Islam is always accepted if sincere. There is an entire surah named At-Tawbah (9). The door of repentance remains open until one's final moments.