((سُبْحَانَ اللَّهِ، وَالْحَمْدُ لِلَّهِ، وَاللَّهُ أَكْبَرُ (ثلاثاً وثلاثين) لاَ إِلَهَ إِلاَّ اللَّهُ وَحْدَهُ لاَ شَرِيكَ لَهُ، لَهُ الْمُلْكُ وَلَهُ الْحَمْدُ وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ)).
How perfect Allah is, all praise is for Allah, and Allah is the greatest.(thirty-three times) None has the right to be worshipped except Allah, alone, without partner, to Him belongs all sovereignty and praise and He is over all things omnipotent.
Muslim 1/418, Whoever says this after every prayer will be forgiven his sins even though they be as the foam of the sea. Based on another authentic hadith - these exclude big sins which require Tawbah Nasuha.