Du'a for children's righteousness

اللَّهُمَّ بَارِكْ لِي فِيهِمْ، وَوَفِّقْهُمْ لِطَاعَتِكَ، وَارْزُقْنِي بِرَّهُمْ

Allahumma barik li fihim, wa waffiqhum lita'atik, warzuqni birrahum

O Allah, bless them for me, grant them success in Your obedience, and grant me their righteousness.

A general supplication, not a narration from the Prophet (peace be upon him).