اَللّٰهُمَّ أَعْطِنِيْ إِيْمَانًا لَّايَرْتَدُّ، وَيَقِيْنًا لَّيْسَ بَعْدَهٗ كُفْرٌ، وَّرَحْمَةً أَنَالُ بِهَا شَرَفَ كَرَامَتِكَ فِي الدُّنْيَا وَالْاٰخِرَةِ ـ
Allaahumma a’tinii iimaanan laa yartadd(u), wa yaqiinan laysa ba’dahuu kufr(un), wa rahmatan anaalu bihaa sharafa karaamatika fid-dunyaa wal-aakhirah.
[‘Abdullah ibn ‘Abbas. Sunan at-Tirmidhi #3341; Mu’jam al-Kabir (Tabarani) 10/284; Kanz al-‘Ummal #3608, 4988 – this du’aa is a part of one comprehensive du’aa that Prophet Muhammad ﷺ said at the end of his nightly Tahajjud salaat]
O Allah, grant me faith that is never shaken, belief so that there is no disbelief thereafter, and mercy by virtue of which I gain the distinction of honor granted by You in this life and the Hereafter.
Mercy by virtue of which: This again affirms that we gain higher ranks through Allah’s mercy, not by dint of our actions.
(Source: Khalid Baig’s transliteration, translation and commentary of du’aa #138 from the Accepted Whispers: Munajat-e-Maqbul)
If you would like to see the full du’aa that is referenced, please take a look at this link inshaallah: https://sunnah.com/tirmidhi/48/50