Sunan Ibn Majah, Volume 4, Book 24, Hadith 2823 (DarusSalam) ⓘ

It was narrated that Kharijah bin Zaid said: “I saw a man asking my father about a man who goes out to fight and buys and sells and trades during his campaign. My father said to him: ‘We were with the Messenger of Allah in Tabuk, and we bought and sold, and he saw us and did not forbid us (to do that).’”

حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ عَبْدِ الْكَرِيمِ، حَدَّثَنَا سُنَيْدُ بْنُ دَاوُدَ، عَنْ خَالِدِ بْنِ حَيَّانَ الرَّقِّيِّ، أَنْبَأَنَا عَلِيُّ بْنُ عُرْوَةَ الْبَارِقِيُّ، حَدَّثَنَا يُونُسُ بْنُ يَزِيدَ، عَنْ أَبِي الزِّنَادِ، عَنْ خَارِجَةَ بْنِ زَيْدٍ، قَالَ رَأَيْتُ رَجُلاً سَأَلَ أَبِي عَنِ الرَّجُلِ، يَغْزُو فَيَشْتَرِي وَيَبِيعُ وَيَتَّجِرُ فِي غَزْوِهِ فَقَالَ لَهُ أَبِي كُنَّا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم بِتَبُوكَ نَشْتَرِي وَنَبِيعُ وَهُوَ يَرَانَا وَلاَ يَنْهَانَا ‏.‏