Al-Samarqandi reported: Abu Umamah al-Bahili, may Allah be pleased with him, said, “Verily, the servant will be given his record on the Day of Resurrection and he will see good deeds that he had not done. He will say: O Lord, from where does these come? Allah will say: These are from people who had backbitten against you while you were unaware.”
Source: Tanbīh al-Ghāfilīn 1/164
عَنْ السمرقندي عَنْ أَبِي أُمَامَةَ الْبَاهِلِيِّ رَضِيَ اللَّهُ تَعَالَى عَنْهُ أَنَّهُ قَالَ إِنَّ الْعَبْدَ لَيُعْطَى كِتَابَهُ يَوْمَ الْقِيَامَةِ فَيَرَى فِيهِ حَسَنَاتٍ لَمْ يَكُنْ عَمِلَهَا فَيَقُولُ يَا رَبُّ مِنْ أَيْنَ لِي هَذَا فَيَقُولُ هَذَا بِمَا اغْتَابَكَ النَّاسُ وَأَنْتَ لَا تَشْعُرُ
1/164 تنبيه الغافلين بأحاديث سيد الأنبياء والمرسلين