Duâaaâ should be made for all the deceased, whether males or females, by saying âAllaahumma aghfir lahum warhamhumâ¦ (O Allaah forgive them and have mercy on themâ¦)â. If they are two you should say, âAllaahumma aghfir lahuma warhamhumaâ¦ (O Allaah, forgive them both and have mercy on them bothâ¦)â.
If the deceased is a child, what should be said in the duâaaâ is: âAllaahumma ajâalhu dhikhran li waalidayhi wa faratan wa shafeeâan mujaaban. Allaahumma aâzim bihi ujoorahuma wa thaqqil bihi mawaazeenahuma wa alhaqhu bi saalih salaf al-muâmineen wajâalhu fi kafaalat Ibraaheem âalayhiâl-salaam, wa qihi bi rahmatika âadhaab il-jaheem (O Allaah, make him a stored treasure for his parents, and a preceding reward and an answered intercessor. O Allaah, increase their reward through him and make their scales weigh heavily. Join him with the righteous believers who have gone on before, place him in the care of Ibraaheem, peace be upon him, and protect him from the torment of Hell by Your mercy).â
Kitaab Majmooâ Fataawa wa Maqaalaat Mutanawwiâah li Samaahat al-Shaykh âAbd al-âAzeez ibn Baaz, 13/145.