مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 2053
Fasting
Voluntary Fasting - Section 1
وَعَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ صَامَ يَوْمًا فِي سَبِيلِ اللَّهِ بَعَّدَ اللَّهُ وَجْهَهُ عَنِ النَّارِ سَبْعِينَ خَرِيفًا»
Abu Sa‘id al-Khudri reported God’s messenger as saying, “If anyone fasts for a day while engaged in jihad, God will remove him* seventy years’ distance from hell.” *Literally, ‘his face’. (Bukhari and Muslim.)
Mishkat al-Masabih, 2053مُتَّفَقٌ عَلَيْهِ (الألباني)