الْحَمْدُ لِلَّهِ الَّذِي وَهَبَ لِي عَلَى الْكِبَرِ إِسْمَاعِيلَ وَإِسْحَاقَ إِنَّ رَبِّي لَسَمِيعُ الدُّعَاءِ
Alhamdulillahilladhi wahaba li 'alal-kibari Isma'ila wa Ishaqa inna Rabbi lasami'ud-du'a
Praise be to Allah who has granted me Ismail and Ishaq in my old age. Indeed, my Lord is the Hearer of supplication.
Recite to thank Allah for the blessing of children
Prophet Ibrahim (AS) showed gratitude for the blessing of children even in old age, affirming that Allah answers prayers.