The Prophet (Sal-Allahu Alaihi Wasallam) said
*If anyone say after every prayer*
*33 times SubhanALLAH,*
*33 times Alhamdulillah,*
*33 times Allahu Akbar,*
*ninety-nine times in all, and says (1 time)to complete a hundred*
لا اِلهَ اِلَّا اللّهُ وَحْدَهُ لا شَرِيكَ لَهُ ، لَهُ الْمُلْكُ وَ لَهُ الْحَمْدُ وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ
La ilaha illal-lah wahdahu la sharika lahu, lahu-l-mulk wa lahu-l-hamd wa huwa Ala kulli shayin qadir
*his sins will be forgiven even If these are equal to the foam of the sea.*
(Sahih Muslim, Book 4, 1243)