During sujood (Prostration)
اَللّٰهُمَّ اغْفِرْلِيْ ذَنْبِۢيْ كُلَّهٗ، دِقَّهٗ وَجِلَّهٗ، وَأَوَّلَهٗ وَاٰخِرَهٗ وَعَلَانِيَتَهٗ وَسِرَّهٗ
O Allah, forgive me all my sins, great and small, the first and the last, those that are apparent and those that are hidden.
References
[Sahih Muslim - 483]