There are some expressions which a man utters three times when he gets up from an assembly he will be forgiven for what happened in the assembly; and no one utters them in an assembly held for a noble cause or for remembrance of Allah but that is stamped with them just as a document is stamped with a signet-ring. These expressions are: Glory be to Thee, O Allah, and I begin with praise of Thee, there is no god but thou; I ask Thy pardon, and return to Thee in repentance.  

أَنَّهُ قَالَ كَلِمَاتٌ لاَ يَتَكَلَّمُ بِهِنَّ أَحَدٌ فِي مَجْلِسِهِ عِنْدَ قِيَامِهِ ثَلاَثَ مَرَّاتٍ إِلاَّ كُفِّرَ بِهِنَّ عَنْهُ وَلاَ يَقُولُهُنَّ فِي مَجْلِسِ خَيْرٍ وَمَجْلِسِ ذِكْرٍ إِلاَّ خُتِمَ لَهُ بِهِنَّ عَلَيْهِ كَمَا يُخْتَمُ بِالْخَاتَمِ عَلَى الصَّحِيفَةِ سُبْحَانَكَ اللَّهُمَّ وَبِحَمْدِكَ لاَ إِلَهَ إِلاَّ أَنْتَ أَسْتَغْفِرُكَ وَأَتُوبُ إِلَيْكَ  

There are some expressions which a man utters three times when he gets up from an assembly he will be forgiven for what happened in the assembly; and no one utters them in an assembly held for a noble cause or for remembrance of Allah but that is stamped with them just as a document is stamped with a signet-ring. These expressions are: Glory be to Thee, O Allah, and I begin with praise of Thee, there is no god but thou; I ask Thy pardon, and return to Thee in repentance. (Using translation from Abū Dāʾūd 4857)  

أَنَّهُ قَالَ «كَلِمَاتٌ لَا يَتَكَلَّمُ بِهِنَّ أَحَدٌ فِي مَجْلِسِ لَغْوٍ أَوْ مَجْلِسِ بَاطِلٍ عِنْدَ قِيَامِهِ ثَلَاثَ مَرَّاتٍ إِلَّا كَفَّرَتْهُنَّ عَنْهُ وَلَا يَقُولُهُنَّ فِي مَجْلِسِ خَيْرٍ وَمَجْلِسِ ذِكْرٍ إِلَّا خُتِمَ لَهُ بِهِنَّ عَلَيْهِ كَمَا يُخْتَمُ بِالْخَاتَمِ عَلَى الصَّحِيفَةِ سُبْحَانَكَ اللَّهُمَّ وَبِحَمْدِكَ لَا إِلَهَ إِلَّا أَنْتَ أَسْتَغْفِرُكَ وَأَتُوبُ إِلَيْكَ»