Is it permissible for Muslims to build a shed for wages for a non-Muslim man to raise cows in it, given their suspicion that he might raise pigs in it, and would their wages for this work be lawful or unlawful?

If a Muslim knows or strongly believes that a disbeliever will use the shed for raising pigs, then it is not permissible to build it or to take payment for it, because doing so constitutes assisting in sin. This is based on the Almighty's saying: "And do not cooperate in sin and aggression." However, if he does not know or does not strongly believe that, then building it and taking payment is not forbidden. If he is in doubt, it is disliked. A Muslim's employment by a disbeliever is permissible as long as it does not involve anything forbidden.