Seeking Refuge Before the Tasleem
اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنْ عَذَابِ الْقَبْرِ، وَمِنْ عَذَابِ جَهَنَّمَ، وَمِنْ فِتْنَةِ الْمَحْيَا وَالْمَمَاتِ، وَمِنْ شَرِّ فِتْنَةِ الْمَسِيحِ الدَّجَّالِ
Allahumma inni a'udhu bika min 'adhabil-qabr, wa min 'adhabi jahannam, wa min fitnatil-mahya wal-mamat, wa min sharri fitnatil-masihid-dajjal.
O Allah, I take refuge with You from the punishment of the grave, from the punishment of Hellfire, from the trials of life and death, and from the evil of the trial of the false messiah.
What it means
Four dangers, two in this world and two beyond it, named in the last moments of the prayer while you are still in front of your Lord. Trials of life are the ones that pull a person away while he is living; the trial of death is the moment faith is tested when it can no longer be corrected.
When and how
Say it after the final tashahhud and blessings upon the Prophet ﷺ, just before giving the salam, in every prayer.
Its virtue
The Prophet ﷺ instructed that when one of us finishes the final tashahhud he should seek refuge from these four, reported in Sahih Muslim 588.
Source
Muslim 588sahih