اللَّهُمَّ اغْفِرْ لَهُ، اللَّهُمَّ ثَبِّتْهُ

O Allāh, forgive him, O Allāh, protect him.

Reference: O Allāh, forgive him, O Allāh, protect him. Abū Dāwud (#3221, 3/315) and al-Hākim (1/370) and he authenticated it and al-Dhahabī agreed with him.

Death, Funeral & Grave — Dua 164 | #islam