Sunan Ibn Majah, Chapter: The Chapters on Etiquette

the Messenger of Allah (saw) said: "Whoever says one hundered times each day: La ilaha illahu wahdahu la sharikalahu, wa lahul-mulku wa lahul hamdu wa huwa ala kulli shayin qadeer (None has the right to be worshipped but Allah alone, with no partner or associate. His is the dominion, all praise is to Him, and He is able to do all things), it will be equivalent to him freeing ten slaves, and one hundered merits will be recorded for him, and one hundered bad deeds will be erased from (his record), and it will be a protection for him against Satan all day until night comes. No one can do anything better then him except one who says more.'"