Yahya related to me from Malik from Sumayy, the mawla of AbuBakr, from Abu Salih as-Samman from Abu Hurayra that the Messenger ofAllah, may Allah bless him and grant him peace, said, "Whoever says'There is no god but Allah, alone, without any partner. The Kingdomand praise belong to Him and He has power over everything' (La ilahailla'llah, wahdahu la sharika lah, lahu'l mulku wa lahu'l hamd, wahuwa ala kulli shay'in qadir) one hundred times a day, it is the samefor him as freeing ten slaves. One hundred good actions are writtenfor him and one hundred wrong actions are erased from him, and it is aprotection from Shaytan for that day until the night. No-one doesanything more excellent than what he does except someone who does morethan that."
USC-MSA web (English) reference: Book 15, Hadith 20
Arabic reference: Book 15, Hadith 492