Sunan Ibn Majah 2823

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 (ﷺ) in Tabuk, and we bought and sold, and he saw us and did not forbid us (to do that).’”