The Messenger of Allah (ﷺ) used to recite this supplication in the prayer:

اَللَّهُمَّ إِنِّي أَعُوْذُ بِكَ مِنْ عَذَابِ الْقَبْرِ، وَأَعُوْذُ بِكَ مِنْ فِتْنَةِ الْمَسِيحِ الدَّجَّالِ، وَأَعُوْذُ بِكَ مِنْ فِتْنَةِ الْمَحْـيَا وَالْمَمَاتِ. اَللَّهُمَّ إِنِّي أَعُوْذُ بِكَ مِنَ الْمَأْثَمِ وَالْمَغْرَمِ

Allaahumma 'innee 'a'oodhu bika min 'adhaabil-qabr, wa 'a'oodhu bika min fitnatil-maseehid-dajjaal, wa 'a'oodhu bika min fitnatil-mahyaa wal-mamaat. Allaahumma 'innee 'a'oodhu bika minal-ma'thami wal-maghram

O Allah, I seek refuge in You from the punishment of the grave, and I seek refuge in You from the trial of the False Messiah, and I seek refuge in You from the trials of life and death. O Allah, I seek refuge in You from sin and from debt. One asks him (the Prophet [ﷺ]), "Why do you seek so much refuge (from Allah) in debt?" In reply, the Prophet (ﷺ) said, "When a person is in debt, he lies when he speaks and breaks his promise.

Reference: Bukhari: 832