عن أبي هريرة قال قال رسول الله صلى الله عليه وسلم صلى الله عليه وسلم من صام رمضان إيمانا واحتسابا غفر له متقدم من ذنبه

Abu Huraira (ra)

The Prophet (peace and blessings of Allaah be upon him) said: Whoever fasted Ramadan in the hope of believing and in the hope of reward, his previous sincerity was forgiven. [1641]

Jami 'At-Tirmidhi, Hadith No. 1641
The tradition of the hadith: Sahih Hadith
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