Sunan an-Nasa'i, Book 25, Hadith 43 (In-Book) ⓘ
It was narrated that Abu Hurairah said: "I heard the Messenger of Allah say: 'The parable of a Mujahid who strives in the cause of Allah - and Allah knows best who in His cause - is that of one who fasts, prays Qiyam, focuses with proper humility, bows and prostrates.'"
أَخْبَرَنَا هَنَّادُ بْنُ السَّرِيِّ، عَنِ ابْنِ الْمُبَارَكِ، عَنْ مَعْمَرٍ، عَنِ الزُّهْرِيِّ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " مَثَلُ الْمُجَاهِدِ فِي سَبِيلِ اللَّهِ - وَاللَّهُ أَعْلَمُ بِمَنْ يُجَاهِدُ فِي سَبِيلِهِ - كَمَثَلِ الصَّائِمِ الْقَائِمِ الْخَاشِعِ الرَّاكِعِ السَّاجِدِ " .
also referenced under: Hadith 3127 (Reference) & Volume 4, Book 25, Hadith 3129 (DarusSalam)