اللَّهُمَّ اغْفِرْ لِي ذَنْبِي كُلَّهُ، دِقَّهُ وَجِلَّهُ، وَأَوَّلَهُ وَآخِرَهُ، وَعَلَانِيَتَهُ وَسِرَّهُ
Allahumma-ghfir li dhanbi kullahu, diqqahu wa jillahu, wa awwalahu wa akhirahu, wa 'alaniyyatahu wa sirrahu
O Allah, forgive all my sins, the small and the great, the first and the last, the open and the secret.
Recite in sujood or during personal supplication
This comprehensive istighfar covers all types of sins in all times and conditions.