Sahih Bukhari Volume 4, Book 59, Hadith 3294

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، أَخْبَرَنَا مَالِكٌ، عَنْ سُمَىٍّ، مَوْلَى أَبِي بَكْرٍ عَنْ أَبِي صَالِحٍ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ مَنْ قَالَ لاَ إِلَهَ إِلاَّ اللَّهُ وَحْدَهُ لاَ شَرِيكَ لَهُ، لَهُ الْمُلْكُ، وَلَهُ الْحَمْدُ، وَهُوَ عَلَى كُلِّ شَىْءٍ قَدِيرٌ‏.‏ فِي يَوْمٍ مِائَةَ مَرَّةٍ، كَانَتْ لَهُ عَدْلَ عَشْرِ رِقَابٍ، وَكُتِبَتْ لَهُ مِائَةُ حَسَنَةٍ، وَمُحِيَتْ عَنْهُ مِائَةُ سَيِّئَةٍ، وَكَانَتْ لَهُ حِرْزًا مِنَ الشَّيْطَانِ يَوْمَهُ ذَلِكَ حَتَّى يُمْسِيَ، وَلَمْ يَأْتِ أَحَدٌ بِأَفْضَلَ مِمَّا جَاءَ بِهِ، إِلاَّ أَحَدٌ عَمِلَ أَكْثَرَ مِنْ ذَلِكَ ‏"‏‏

Narrated By Abu Huraira : Allah's Apostle said, "If one says one-hundred times in one day: "None has the right to be worshipped but Allah, the Alone Who has no partners, to Him belongs Dominion and to Him belong all the Praises, and He has power over all things (i.e. Omnipotent)", one will get the reward of manumitting ten slaves, and one-hundred good deeds will be written in his account, and one-hundred bad deeds will be wiped off or erased from his account, and on that day he will be protected from the morning till evening from Satan, and nobody will be superior to him except one who has done more than that which he has done."