Sunan an-Nasa'i 1347
It was narrated that Muslim bin Abi Bakrah said:
"My father used to say following every prayer: 'Allahumma inni a-udhu bika min al-kufri wal-faqri wa 'adhab al-qabr. ( O Allah, I seek refuge with You from Kufr, poverty, and the torment of the grave)' and I used to say them (these words). My father said: 'O my son, from whom did you learn this?' I said: 'From you. He said: "The Messenger of Allah (ﷺ) used to say them following the prayer.'"
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ عُثْمَانَ الشَّحَّامِ، عَنْ مُسْلِمِ بْنِ أَبِي بَكْرَةَ، قَالَ كَانَ أَبِي يَقُولُ فِي دُبُرِ الصَّلاَةِ اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنَ الْكُفْرِ وَالْفَقْرِ وَعَذَابِ الْقَبْرِ فَكُنْتُ أَقُولُهُنَّ فَقَالَ أَبِي أَىْ بُنَىَّ عَمَّنْ أَخَذْتَ هَذَا قُلْتُ عَنْكَ ‏.‏ قَالَ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يَقُولُهُنَّ فِي دُبُرِ الصَّلاَةِ ‏.‏