" مَنْ صَامَ يَوْمًا فِي سَبِيلِ اللَّهِ بَاعَدَ اللَّهُ بِذَلِكَ الْيَوْمِ حَرَّ جَهَنَّمَ عَنْ وَجْهِهِ سَبْعِينَ خَرِيفًا "
It was narrated from Abu Saeed Al-Khudri that the Prophet said: "Whoever fasts a day in the cause of Allah, Allah will separate his face from the heat of Hell (a distance of) seventy autumns."