It is narrated on the authority of Wasila ibn al-Aska (RA) that he said, 'The Messenger of Allah (ﷺ) performed the janaza of a Muslim man with us. There I heard him said -

اَللَّهُمَّ إِنَّ (فُلَانَ بْنَ فُلَانٍ) فِي ذِمَّتِكَ وَحَبْلِ جِوَارِكَ فَقِهِ مِنْ فِتْنَةِ الْقَبْرِ وَعَذَابِ النَّارِ وَأَنْتَ أَهْلُ الْوَفَاءِ وَالْحَقِّ اَللَّهُمَّ فَاغْفِرْ لَهُ وَارْحَمْهُ إِنَّكَ أَنْتَ الْغَفُوْرُ الرَّحِيْمُ

Allaahumma 'inna (fulanabna fulan) fee dhimmatika, wa habli jiwaarika, faqihi min fitnatil-qabri wa 'adhaabin-naari, wa 'Anta 'ahlul-wafaa'i walhaqq. Allaahumma Faghfir lahu warhamhu 'innaka 'Antal-Ghafoorur-Raheem.

O Allah, surely [name the person] is under Your protection, and in the rope of Your security, so save him from the trial of the grave and from the punishment of the Fire. You fulfill promises and grant rights, so forgive him and have mercy on him. Surely You are Most Forgiving, Most Merciful.

Reference: Sahih. Abu Dawud: 3202