كتاب الْمَسَاجِدِ وَمَوَاضِعِ الصَّلاَةِ
5
The Book of Mosques and Places of Prayer
(25)
Chapter: From what refuge is to be sought when in salat
(25)
باب مَا يُسْتَعَاذُ مِنْهُ فِي الصَّلاَةِ ‏

'A'isha, the wife of the Messenger of Allah (ﷺ) reported:

The Apostle of Allah (ﷺ) used to supplicate in prayer thus:" O Allah! I seek refuge with Thee from the torment of the grave, and I seek refuge with Thee from the trial of the Masih al-Dajjal (Antichrist) and I seek refuge with Thee from the trial of life and death. O Allah! I seek refuge with Thee from sin and debt." She ('A'isha) reported: Someone said to him - (the Holy Prophet): Messenger of Allah! why is it that you so often seek refuge from debt? He said: When a (person) incurs debt, (he is obliged) to tell lies and break promise.
حَدَّثَنِي أَبُو بَكْرِ بْنُ إِسْحَاقَ، أَخْبَرَنَا أَبُو الْيَمَانِ، أَخْبَرَنَا شُعَيْبٌ، عَنِ الزُّهْرِيِّ، قَالَ أَخْبَرَنِي عُرْوَةُ بْنُ الزُّبَيْرِ، أَنَّ عَائِشَةَ، زَوْجَ النَّبِيِّ صلى الله عليه وسلم أَخْبَرَتْهُ أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ يَدْعُو فِي الصَّلاَةِ ‏"‏ اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنْ عَذَابِ الْقَبْرِ وَأَعُوذُ بِكَ مِنْ فِتْنَةِ الْمَسِيحِ الدَّجَّالِ وَأَعُوذُ بِكَ مِنْ فِتْنَةِ الْمَحْيَا وَالْمَمَاتِ اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنَ الْمَأْثَمِ وَالْمَغْرَمِ ‏"‏ ‏.‏ قَالَتْ فَقَالَ لَهُ قَائِلٌ مَا أَكْثَرَ مَا تَسْتَعِيذُ مِنَ الْمَغْرَمِ يَا رَسُولَ اللَّهِ ‏.‏ فَقَالَ ‏"‏ إِنَّ الرَّجُلَ إِذَا غَرِمَ حَدَّثَ فَكَذَبَ وَوَعَدَ فَأَخْلَفَ ‏"‏ ‏.‏
Reference : Sahih Muslim 589
In-book reference : Book 5, Hadith 163
USC-MSA web (English) reference : Book 4, Hadith 1218
  (deprecated numbering scheme)