The Book of Repentance
Ṣaḥīḥ Muslim 7014
يَجِيءُ يَوْمَ الْقِيَامَةِ نَاسٌ مِنَ الْمُسْلِمِينَ بِذُنُوبٍ أَمْثَالِ الْجِبَالِ فَيَغْفِرُهَا اللَّهُ لَهُمْ وَيَضَعُهَا عَلَى الْيَهُودِ وَالنَّصَارَى
yajīʾu yawma al-qiyāmah nāsun mina al-muslimīna bidhunūbin amthāli al-jibāli fayaghfiruhā-Llāh lahum wayaḍaʿuhā ʿalā al-yahūdi wa-an-naṣārā
Transliteration generated from the Arabic vowel marks
The full narration
Abu Burda reported Allah's Messenger (ﷺ) as saying:There would come people amongst the Muslims on the Day of Resurrection with as heavy sins as a mountain, and Allah would forgive them and He would place in their stead the Jews and the Christians. (As far as I think), Abu Raub said: I do not know as to who is in doubt. Abu Burda said: I narrated it to 'Umar b. 'Abd al-'Aziz, whereupon he said: Was it your father who narrated it to you from Allah's Apostle (ﷺ)? I said: Yes
Source
Ṣaḥīḥ Muslim · 7014