Every servant of Allah who observes fast for a day in the way of Allah, Allah would remove, because of this day, his face farther from the Fire (of Hell) to the extent of seventy years' distance. (Using translation from Muslim 1153a)
أَنَّهُ سَمِعَ رَسُولَ اللهِ ﷺ يَقُولُ «مَا مِنْ عَبْدٍ يَصُومُ يَوْمًا فِي سَبِيلِ اللهِ إِلَّا بَعَّدَ اللهُ بِذَلِكَ الْيَوْمِ وَجْهَهُ عَنِ النَّارِ سَبْعِينَ خَرِيفًا»