Musannaf Ibn Abi Shaybah

Hazrat Khalid bin Abi Imran (may Allah have mercy on him) says that I asked Hazrat Qasim bin Muhammad (may Allah have mercy on him) and Hazrat Salim bin Abdullah (may Allah have mercy on him), both of them: We have a slave who works as a potter in the enemy's territory. Then he sells those pots and accumulates a considerable amount of wealth, and he also spends from it on us. They replied: There is no harm in this.