Riyad as-Salihin, Book 1, Hadith 18 (In-Book)

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

وعن أبي عبد الرحمن عبد الله بن عمر بن الخطاب رضي الله عنهما عن النبي صلى الله عليه وسلم قال‏:‏ ‏ "‏ إن الله عز وجل يقبل توبة العبد ما لم يغرغر‏" ‏ ‏(‏‏(‏رواه الترمذي وقال‏:‏ حديث حسن‏)‏‏)‏‏.‏

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