Sunan an-Nasa'i 2248
سنن النسائي#2248Sahihأَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ عَبْدِ الْحَكَمِ، عَنْ شُعَيْبٍ، قَالَ أَنْبَأَنَا اللَّيْثُ، عَنِ ابْنِ الْهَادِ، عَنْ سُهَيْلٍ، عَنِ ابْنِ أَبِي عَيَّاشٍ، عَنْ أَبِي سَعِيدٍ، أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " مَا مِنْ عَبْدٍ يَصُومُ يَوْمًا فِي سَبِيلِ اللَّهِ عَزَّ وَجَلَّ إِلاَّ بَعَّدَ اللَّهُ عَزَّ وَجَلَّ بِذَلِكَ الْيَوْمِ وَجْهَهُ عَنِ النَّارِ سَبْعِينَ خَرِيفًا " .
It was narrated from Abu Saeed that he heard the Messenger of Allah say:"There is no worshipper who fasts a day in the cause of Allah, the mighty and sublime, but Allah the mighty and sublime, will separate his face from the fire by (a distance of) seventy autumns in return for that day
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 22:159