It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Whoever, after every prayer, recites "Allahu Akbar" thirty-three times, "Subhan Allah" thirty-three times, and "Alhamdulillah" thirty-three times, thus reaching ninety-nine, and to complete one hundred says at the end: "La ilaha illallah wahdahu la sharika lahu, lahul mulk wa lahul hamd wa huwa 'ala kulli shay'in qadeer," then all his sins will be forgiven, even if they are as much as the foam of the sea.