Du'a for a mother's forgiveness

اللَّهُمَّ اغْفِرْ لَهَا ذَنْبَهَا كُلَّهُ، دِقَّهُ وَجِلَّهُ، وَأَوَّلَهُ وَآخِرَهُ، وَعَلَانِيَتَهُ وَسِرَّهُ

Allahummaghfir laha dhanbaha kullahu, diqqahu wa jillahu, wa awwalahu wa akhirahu, wa 'alaniyatahu wa sirrahu

O Allah, forgive all of her sins, the small and the great, the first and the last, the open and the secret.

Adapted into the third person feminine from Ṣaḥīḥ Muslim 483.