سُبْحَانَ اللَّهِ وَبِحَمْدِهِ، أَسْتَغْفِرُ اللَّهَ وَأَتُوبُ إِلَيْهِ
Subhanallahi wa bihamdihi, astaghfirullaha wa atubu ilayh
Glory be to Allah and praise be to Him. I seek forgiveness from Allah and repent to Him.
Recite frequently or after gatherings
The Prophet (PBUH) would say this when getting up from a gathering, and Aisha (RA) noted he said it often after Surah An-Nasr was revealed.