'Abdullah bin 'Umar bin Al-Khattab (May Allah be pleased with them) reported that:

The Prophet (ﷺ) said, "Allah accepts a slave's repentance as long as the latter is not on his death bed (that is, before the soul of the dying person reaches the throat)".

[At-Tirmidhi, who categorised it as Hadith Hasan].

Arabic/English book reference : Book 1, Hadith 18