عن أبي هريرة رضي الله عنه:
أن رسول الله صلى الله عليه وسلم قال: من قال: لا إله إلا الله وحده لا شريك له، له الملك وله الحمد، وهو على كل شيء قدير. في يوم مائة مرة، كانت له عدل عشر رقاب، وكتبت له مائة حسنة، ومحيت عنه مائة سيئة، وكانت له حرزاً من الشيطان يومه ذلك حتى يمسي، ولم يأت أحد بأفضل مما جاء به إلا رجل عمل أكثر منه رواہ البخاری

Narrated Abu Hurairah Allah's Apostle said," Whoever says: "La ilaha illAllahu wahdahu la Sharika lahu lahul Mulku wa lahul Hamdu wa huwa 'ala kulli Shai'in Qadir," one hundred times will get the same reward as given for manumitting ten slaves; and one hundred good deeds will be written in his accounts, and one hundred sins will be deducted from his accounts, and it (his saying) will be a shield for him from Satan on that day till night, and nobody will be able to do a better deed except the one who does more than him
(Sahih Bukhari)

Vocabulary of the Hadith:
hundred times مائة مرة
same reward/equal to عدل
deducted/erased محيت
shield حرزاً

Lessons of the Hadith Just as the most hated of sins in the sight of Allah is Shirk, Tawheed is the most beloved. That is why no one can do a better deed than the person who revises his tawheed by saying this phrase:

Allah loves people who revise their Tawheed, as can be seen from the tremendous reward for just saying a phrase that affirms Tawheed.

It shows the mercy of Allah in that it only takes 10 minutes to say it a hundred times, but Allah shields us against shaitaan for the entire day

Allah frees us from HellFire if we free one Muslim slave (Bukhari). Here Allah is rewarding us with freeing ten slaves

Wassalam