Having many children who live and die upon Islam is beneficial even if they do not make Dua for you particularly. Since you as a Muslim parent are the source of their Islam, thus all the good deeds that they do will add up as Sadaqah Jariyah (ongoing charity) for you In-sha-Allah. This will continue down the line to your grandchildren and great-grandchildren and so on InshaAllah…
Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said, “When the human being dies, his deeds end except for three: ongoing charity, beneficial knowledge, or a righteous child who prays for him.” (Sahih Muslim 1631)
In Mirqat al-Mafatih (commentary on Mishkat al-Masabih), it is mentioned:
“The Prophet specifically mentioned the child’s supplication to encourage the child to pray for his father.
It has been said that the parent receives the reward for the righteous deeds of the child, whether the child prays for the parent or not,
… just as the one who plants a tree receives a reward when its fruit is eaten, whether the one who eats the fruit supplicates for him or not.” (Mirqat al-Mafatih, commentary on Mishkat al-Masabih, 1/453, Rashidiyah Library edition).
Note: This is just one of the many benefits of having a lot of children.
