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 1896 d

It has been narrated (through a still different chain of transmitters) on the authority of Abu Sa'id Khudrl that the Messenger of Allah (ﷺ) despatched a force to Banu Lihyan. (and said:

) One man from every two should join the force. Then he said to those who stayed behind: Those of you who will look well after the family and wealth of those who are going on the expedition will be getting half the reward of the warriors.
وَحَدَّثَنَا سَعِيدُ بْنُ مَنْصُورٍ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ وَهْبٍ، أَخْبَرَنِي عَمْرُو بْنُ الْحَارِثِ، عَنْ يَزِيدَ بْنِ أَبِي حَبِيبٍ، عَنْ يَزِيدَ بْنِ أَبِي سَعِيدٍ، مَوْلَى الْمَهْرِيِّ عَنْ أَبِيهِ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم بَعَثَ إِلَى بَنِي لَحْيَانَ ‏"‏ لِيَخْرُجْ مِنْ كُلِّ رَجُلَيْنِ رَجُلٌ ‏"‏ ‏.‏ ثُمَّ قَالَ لِلْقَاعِدِ ‏"‏ أَيُّكُمْ خَلَفَ الْخَارِجَ فِي أَهْلِهِ وَمَالِهِ بِخَيْرٍ كَانَ لَهُ مِثْلُ نِصْفِ أَجْرِ الْخَارِجِ ‏"‏ ‏.‏
Reference : Sahih Muslim 1896d
In-book reference : Book 33, Hadith 202
USC-MSA web (English) reference : Book 20, Hadith 4672
  (deprecated numbering scheme)