It is narrated from Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Whoever says ten times in the morning: 'La ilaha illallahu wahdahu la sharika lahu, lahul-mulku wa lahul-hamdu, yuhyi wa yumitu, wa huwa 'ala kulli shay'in qadir' (There is no god but Allah, alone, He has no partner; His is the dominion and His is the praise; He gives life and causes death, and He has power over all things), then for each time he says it, ten (good deeds are written for him and ten) sins (are erased), Allah raises him ten degrees by it, they become for him equal to freeing ten slaves, they become a guard for him from morning till evening, and on that day he does no deed that overpowers them; and if he says it in the evening, it is likewise."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3868