(3) باب مَا جَاءَ فِي فَضْلِ الصَّوْمِ فِي سَبِيلِ اللَّهِ
Narrated Abu Al-Aswad :
From 'Urwah [bin Az-Zubair], and Sulaiman bin Yasar, that they reported to him from Abu Hurairah that the Prophet (ﷺ) said: "Whoever fasts a day in the cause of Allah, Allah shall distance him from the Fire by seventy autumns." One of them said "seventy" and the other said: "forty".[Abu 'Eisa said:] This Hadith is a Gharib Hadith from this route. Abu Al-Aswad's name is Muhammad bin 'Abdur-Rahman bin Nawfal Al-Asadi Al-Madani.There are narrations on this topic from Abu Sa'eed, Anas, 'Uqbah bin 'Amir, and Abu Umamah
Reference: Jami` at-Tirmidhi 1622
In-book reference: Book 22, Hadith 4
English translation: Vol. 3, Book 20, Hadith 1622