22. The Book on Virtues of Jihad - كتاب فضائل الجهاد عن رسول الله صلى الله عليه وسلم
3) Chapter: What Has Been Related About The Virtue Of Fasting In The Cause Of Allah
Narrated Abu Sa’id Al Khudri :
That the Prophet (ﷺ) said: "A worshipper does not fast a day in the cause of Allah except that, that day (of fasting) distances the Fire from his face by seventy autumns."