Yahya related to me from Malik from Abu'zZubayr al-Makki from Tawus al-Yamani from Abdullah ibn Abbas that the Messenger of Allah ﷺ used to teach this dua in the same way that he would teach them a sura of the Qur'an, "O Allah, I seek refuge in You from the torment of Jahannam, and I seek refuge in You from the trial of the Dajjal, and I seek refuge in You from the trial of life and death."
Allahumma inniy audhu bika min adhabi jahannama, wa audhu bika min adhabi'l-qabri, wa audhu bika min fitnati'l-mahya wa mamati.

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ أَبِي الزُّبَيْرِ الْمَكِّيِّ، عَنْ طَاوُسٍ الْيَمَانِيِّ، عَنْ عَبْدِ اللَّهِ بْنِ عَبَّاسٍ، أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُعَلِّمُهُمْ هَذَا الدُّعَاءَ كَمَا يُعَلِّمُهُمُ السُّورَةَ مِنَ الْقُرْآنِ يَقُولُ " اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنْ عَذَابِ جَهَنَّمَ وَأَعُوذُ بِكَ مِنْ عَذَابِ الْقَبْرِ وَأَعُوذُ بِكَ مِنْ فِتْنَةِ الْمَسِيحِ الدَّجَّالِ وَأَعُوذُ بِكَ مِنْ فِتْنَةِ الْمَحْيَا وَالْمَمَاتِ " .