la ilaha illallahu wahdahu la sharika lahu lahul mulku
It was narrated from Abu Hurairah (ra) that the Messenger of Allah (s.a.w) said: "Whoever says: 'La ilaha illallahu wahdahu Ia sharika lahu, lahul-mulku wa lahul-hamdu, wa huwa 'ala kulli shay'in qadir (None has the right to be worshiped but Allah alone with no partner or associate, His is the dominion, to Him is praise and He has power over all things)' one hundred times in a day, it will be the equivalent of his freeing ten slaves, and one hundred good deeds will be recorded for him, and one hundred bad deeds will be erased for him, and it will be a protection for him against the Shaitan all day until evening comes, and no one will do anything better than what he has done except one who does more than that. (Sahih Bukhari: 6842)