كتاب الإمارة
33  
The Book on Government
(38)
Chapter: The virtue of helping the warrior who is fighting in the cause of Allah with mounts etc., and looking after his family in his absence
(38)
باب فَضْلِ إِعَانَةِ الْغَازِي فِي سَبِيلِ اللَّهِ بِمَرْكُوبٍ وَغَيْرِهِ وَخِلاَفَتِهِ فِي أَهْلِهِ بِخَيْرٍ
Sahih Muslim 1895 a

It has been narrated on the authority of Zaid b. Khalid al-Juhani that the Messenger of Allah (ﷺ) said:

Anybody who equips a warrior (going to fight) in the way of Allah (is like one who actually) fights. And anybody who looks well after his family in his absence (is also like one who actually) fights.
وَحَدَّثَنَا سَعِيدُ بْنُ مَنْصُورٍ، وَأَبُو الطَّاهِرِ، قَالَ أَبُو الطَّاهِرِ أَخْبَرَنَا ابْنُ وَهْبٍ، وَقَالَ، سَعِيدٌ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ وَهْبٍ، أَخْبَرَنِي عَمْرُو بْنُ الْحَارِثِ، عَنْ بُكَيْرِ بْنِ الأَشَجِّ، عَنْ بُسْرِ، بْنِ سَعِيدٍ عَنْ زَيْدِ بْنِ خَالِدٍ الْجُهَنِيِّ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم أَنَّهُ قَالَ ‏ "‏ مَنْ جَهَّزَ غَازِيًا فِي سَبِيلِ اللَّهِ فَقَدْ غَزَا وَمَنْ خَلَفَهُ فِي أَهْلِهِ بِخَيْرٍ فَقَدْ غَزَا ‏"‏ ‏.‏
Reference : Sahih Muslim 1895a
In-book reference : Book 33, Hadith 198
USC-MSA web (English) reference : Book 20, Hadith 4668
  (deprecated numbering scheme)