Sunan Ibn Majah 3798
It was narrated from Abu Hurairah that :
the Messenger of Allah(ﷺ) said: "Whoever says one hundered times each day: La ilaha illahu wahdahu la sharikalahu, wa lahul-mulku wa lahul hamduwa 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.'"
حَدَّثَنَا أَبُو بَكْرٍ، حَدَّثَنَا زَيْدُ بْنُ الْحُبَابِ، عَنْ مَالِكِ بْنِ أَنَسٍ، أَخْبَرَنِي سُمَىٌّ، مَوْلَى أَبِي بَكْرٍ عَنْ أَبِي صَالِحٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏
"‏ مَنْ قَالَ فِي يَوْمٍ مِائَةَ مَرَّةٍ لاَ إِلَهَ إِلاَّ اللَّهُ وَحْدَهُ لاَ شَرِيكَ لَهُ لَهُ الْمُلْكُ وَلَهُ الْحَمْدُ وَهُوَ عَلَى كُلِّ شَىْءٍ قَدِيرٌ كَانَ لَهُ عَدْلَ عَشْرِ رِقَابٍ وَكُتِبَتْ لَهُ مِائَةُ حَسَنَةٍ وَمُحِيَ عَنْهُ مِائَةُ سَيِّئَةٍ وَكُنَّ لَهُ حِرْزًا مِنَ الشَّيْطَانِ سَائِرَ يَوْمِهِ إِلَى اللَّيْلِ وَلَمْ يَأْتِ أَحَدٌ بِأَفْضَلَ مِمَّا أَتَى بِهِ إِلاَّ مَنْ قَالَ أَكْثَرَ ‏"‏ ‏.‏