Astaghfirullāh
After every prayer, and throughout the day
Arabic
أَسْتَغْفِرُ اللَّهَ
Transliteration
Astaghfirullāh.
English
"I seek the forgiveness of Allah."
Source: Ṣaḥīḥ Muslim 591
Context
The Prophet ﷺ would say this three times at the end of every obligatory prayer.