Sunan an-Nasa'i 2244
سنن النسائي#2244Sahihأَخْبَرَنَا يُونُسُ بْنُ عَبْدِ الأَعْلَى، قَالَ أَخْبَرَنِي أَنَسٌ، عَنْ سُهَيْلِ بْنِ أَبِي صَالِحٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم قَالَ " مَنْ صَامَ يَوْمًا فِي سَبِيلِ اللَّهِ عَزَّ وَجَلَّ زَحْزَحَ اللَّهُ وَجْهَهُ عَنِ النَّارِ بِذَلِكَ الْيَوْمِ سَبْعِينَ خَرِيفًا " .
It was narrated from Abu Hurairah that the Messenger of Allah said:"Whoever fasts one day in the cause of Allah, the Mighty and sublime, Allah will remove his face away from the fire in return for the day (the distance of) seventy autumns
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: 22:155