اللَّهُمَّ اغْفِرْ لَهُ وَارْحَمْهُ وَأَدْخِلْهُ الْجَنَّةَ وَأَعِذْهُ مِنْ عَذَابِ الْقَبْرِ
Allahummaghfir lahu warhamhu wa adkhilhul-jannata wa a'idhhu min 'adhabil-qabr
O Allah, forgive him, have mercy on him, admit him to Paradise, and protect him from the punishment of the grave.
This concise du'a covers the essential requests for the deceased. The Prophet ﷺ said: "When a person dies, his deeds come to an end except for three: ongoing charity, beneficial knowledge, or a righteous child who prays for him" (Sahih Muslim 1631). Du'a for deceased parents is one of the greatest acts of birr (righteousness) a child can do.
Related Du'as
اللَّهُمَّ اجْعَلْ قَبْرِي رَوْضَةً مِنْ رِيَاضِ الْجَنَّةِ وَلَا تَجْعَلْهُ حُفْرَةً مِنْ حُفَرِ النَّارِ
O Allah, make my grave a garden from the gardens of Paradise, and do not make it a pit from the pits of the Fire.
Hasanاللَّهُمَّ اغْفِرْ لَهُ وَارْفَعْ دَرَجَتَهُ فِي الْمَهْدِيِّينَ وَافْسَحْ لَهُ فِي قَبْرِهِ وَنَوِّرْ لَهُ فِيهِ
O Allah, forgive him, raise his rank among the guided, make his grave spacious, and illuminate it for him.
Sahihاللَّهُمَّ ثَبِّتْنِي عِنْدَ السُّؤَالِ، اللَّهُمَّ ثَبِّتْنِي بِالْقَوْلِ الثَّابِتِ فِي الْحَيَاةِ الدُّنْيَا وَفِي الْآخِرَةِ
O Allah, keep me firm at the time of questioning. O Allah, make me firm with the firm word in the life of this world and in the Hereafter.
Sahihاللَّهُمَّ إِنْ كَانَ مُحْسِنًا فَزِدْ فِي إِحْسَانِهِ وَإِنْ كَانَ مُسِيئًا فَتَجَاوَزْ عَنْ سَيِّئَاتِهِ
O Allah, if he was a doer of good, then increase his good deeds, and if he was a wrongdoer, then overlook his misdeeds.
Hasan