اللًّهُمَّ اغْفِرْ لِي ذَنْبِي كُلَّهُ، دِقَّهُ وَجِلَّهُ، وَأَوَّلَهُ وَآخِرَهُ، وَعَلانِيَتَهُ وَسِرَّهُ

O Allāh, forgive me all of my sins, the small and great of them, the first and last of them, and the apparent and hidden of them.

Reference: Muslim (#483, 1/350).