[for a male]
اللَّهُمَّ اغْفِرْ لِ [mention the person's name] وَارْفَعْ دَرَجَتَهُ فِي الْمَهْدِيِّينَ ، وَاخْلُفْهُ فِي عَقِبِهِ فِي الْغَابِرِينَ ، وَاغْفِرْ لَنَا وَلَهُ يَا رَبَّ الْعَالَمِينَ ، وَافْسَحْ لَهُ فِي قَبْرِهِ وَنَوِّرْ لَهُ فِيهِ
[for a female]
اللَّهُمَّ اغْفِرْ لِ [mention the person's name] وَارْفَعْ دَرَجَتَهَا فِي الْمَهْدِيِّينَ ، وَاخْلُفْهَا فِي عَقِبِهَا فِي الْغَابِرِينَ ، وَاغْفِرْ لَنَا وَلَهَا يَا رَبَّ الْعَالَمِينَ ، وَافْسَحْ لَهَا فِي قَبْرِهَا وَنَوِّرْ لَهَا فِيهِ
اللَّهُمَّ اغْفِرْ لِ [mention the person's name] وَارْفَعْ دَرَجَتَهُ فِي الْمَهْدِيِّينَ ، وَاخْلُفْهُ فِي عَقِبِهِ فِي الْغَابِرِينَ ، وَاغْفِرْ لَنَا وَلَهُ يَا رَبَّ الْعَالَمِينَ ، وَافْسَحْ لَهُ فِي قَبْرِهِ وَنَوِّرْ لَهُ فِيهِ
[for a female]
اللَّهُمَّ اغْفِرْ لِ [mention the person's name] وَارْفَعْ دَرَجَتَهَا فِي الْمَهْدِيِّينَ ، وَاخْلُفْهَا فِي عَقِبِهَا فِي الْغَابِرِينَ ، وَاغْفِرْ لَنَا وَلَهَا يَا رَبَّ الْعَالَمِينَ ، وَافْسَحْ لَهَا فِي قَبْرِهَا وَنَوِّرْ لَهَا فِيهِ
Translation 
O Allah, forgive – [so-and-so] - and raise his rank among the rightly guided, and be a successor to whom he has left behind, and forgive us and him O Lord of the worlds. Make spacious his grave and illuminate it for him.
Transliteration
[for a male]
allahumm-aghfir li [mention the person's name] warfa‛ darajatahu fil-mahdiyyiyna, wakhlufhu fee ‛aqibihi fil-ghaabireena, waghfir lanaa wa lahu yaa rabbal-‛aalameena, wafsaḥ lahu fee qabrihi wa nawwir lahu feeh
[for a female]
allahumm-aghfir li [mention the person's name] warfa‛ darajatahaa fil-mahdiyyiyna, wakhlufhaa fee ‛aqibihaa fil-ghaabireena, waghfir lanaa wa lahaa yaa rabbal-‛aalameena, wafsaḥ lahaa fee qabrihaa wa nawwir lahaa feeh
allahumm-aghfir li [mention the person's name] warfa‛ darajatahu fil-mahdiyyiyna, wakhlufhu fee ‛aqibihi fil-ghaabireena, waghfir lanaa wa lahu yaa rabbal-‛aalameena, wafsaḥ lahu fee qabrihi wa nawwir lahu feeh
[for a female]
allahumm-aghfir li [mention the person's name] warfa‛ darajatahaa fil-mahdiyyiyna, wakhlufhaa fee ‛aqibihaa fil-ghaabireena, waghfir lanaa wa lahaa yaa rabbal-‛aalameena, wafsaḥ lahaa fee qabrihaa wa nawwir lahaa feeh
Sources:
Muslim No# 920; Abu Dawud No# 3118
