Du'a for a father's repentance

اللَّهُمَّ تَقَبَّلْ تَوْبَتَهُ، وَأَجِبْ دَعْوَتَهُ

Allahumma taqabbal tawbatahu, wa ajib da'watahu

O Allah, accept his repentance and answer his supplication.

Adapted into the third person masculine from Sunan al-Tirmidhī 3551.