Sunan Ibn Majah 1393
سنن ابن ماجه#1393Sahihحَدَّثَنَا مُحَمَّدُ بْنُ يَحْيَى، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، عَنْ مَعْمَرٍ، عَنِ الزُّهْرِيِّ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ كَعْبِ بْنِ مَالِكٍ، عَنْ أَبِيهِ، قَالَ لَمَّا تَابَ اللَّهُ عَلَيْهِ خَرَّ سَاجِدًا .
It was narrated from ‘Abdur-Rahman bin Ka’b bin Malik that his father said that when Allah accepted his repentance, he fell down prostrate
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih
In-book reference: 5:591