اَللَّهُمَّ اغْفِرْ لَهُ، وَارْفَعْ دَرَجَتَهُ فِي الْمَهْدِيِّينَ، وَاخْلُفْهُ فِي عَقِبِهِ فِي الْغَابِرِيْنَ، وَاغْفِرْ لَنَا وَلَهُ يَا رَبَّ الْعَالَمِيْنَ، وَافْسَحْ لَهُ فِي قَبْرِهِ، وَنَوِّرْ لَهُ فِيهِ

Alla-humma'gfir lahu (person's name), warfa'a darajatahu fil mahdiyin, wa'khlufhu fi 'aqibihi fil ga-birin, wagfir lana wa lahu ya rabbal' a-lamin, wafsa'ah lahu fi qabrihi, wa nau-wir lahu fihi

O Allah, forgive him (person's name), raise his degree among those who are rightly guided, grant him a successor in his descendants who remain. Forgive us and him, O Lord of the Universe, and make his grave spacious, and grant him light in it. The Messenger of Allah (ﷺ) came to Abu Salama (RA) (as he died). His eyes were fixedly open. Rasoolullah (ﷺ) closed them, and then said: When the soul is taken away the sight follows it. Some of the people of his family wept and wailed. So he said: Do not supplicate for yourselves anything but good, for angels say "Amen" to what you say. He then said- (The dua is mentioned above)

Reference: Muslim: 920