مَنْ قَالَ دُبُرَ كُلِّ صَلَاةٍ: سُبْحَانَ اللَّهِ ثَلَاثًا وَثَلَاثِينَ، وَالْحَمْدُ لِلَّهِ ثَلَاثًا وَثَلَاثِينَ، وَاللَّهُ أَكْبَرُ ثَلَاثًا وَثَلَاثِينَ، فَتِلْكَ تِسْعَةٌ وَتِسْعُونَ، وَقَالَ تَمَامَ الْمِائَةِ: لَا إِلَهَ إِلَّا اللَّهُ وَحْدَهُ لَا شَرِيكَ لَهُ، لَهُ الْمُلْكُ وَلَهُ الْحَمْدُ وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ، غُفِرَتْ خَطَايَاهُ وَإِنْ كَانَتْ مِثْلَ زَبَدِ الْبَحْرِ
Whoever says after every prayer: Subhanallah (33 times), Alhamdulillah (33 times), Allahu Akbar (33 times), making ninety-nine, and then completes one hundred by saying: There is no god but Allah alone with no partner, to Him belongs dominion and praise and He is over all things competent - his sins will be forgiven even if they are like the foam of the sea.
Abu Hurairah•Sahih Muslim•Prayer