“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).’”
Sunan Ibn Majah Book 24, Hadith 71