the sultan through the troops’ revenue allotments: is this lawful or unlawful?
He replied:
If a man is in need and the source of revenue contains both lawful and unlawful funds, or is of doubtful lawfulness, then, if he has no alternative but to accept it, he should spend it on external expenses, such as fodder for his mount, government levies, and similar expenses. If he gives it in charity to the poor, or intends it as charity on behalf of those entitled to it, that is good. Allah knows best.
He was also asked:
About a man who holds a concession involving atrūn. The customary practice among Muslims was for poor men to buy atrūn and sell it for three copper coins per ratl. During the reign of Baybars, someone took over the atrūn concession on the condition that no one could sell or buy except through the concession holder, at twenty-three dirhams per qintār. Is this lawful or unlawful?
He replied:
Where someone has acquired atrūn lawfully, no one may compel anyone to buy from him or prevent anyone from buying from someone else. Rather, if he acquires it lawfully and sells it as other Muslim merchandise is sold, that is permissible.