Contracts of hire (ijārah) and reward-based commission (juʿālah) of this sort can be described as neither wholly valid nor wholly void. From the hirer’s side they are valid, meaning he remains liable for the stipulated fee or wage; from the worker’s side they are defective, for he is forbidden to benefit from that payment. The Sharīʿah offers other parallels to this ruling.

On that basis, Aḥmad’s explicit disapproval of supervising a Christian’s vineyard is perfectly consistent with what has been stated. We forbid the worker to undertake the task and to keep its price, yet we still adjudicate in his favor for the rent that is due to him. Were we not to do so, the sinners would reap a great advantage: anyone who hired a person to help him commit sin would obtain the benefit and then pay nothing, even though such people are unworthy of being aided.

This differs from a case where someone hands over a deed that in itself has no value whatsoever.

As for the prostitute, the singer, the professional mourner, and the like—when they have taken their fees and then repent—should they give the money in charity, or must they return it to those who paid them? There are two opinions. The sounder view is that we do not return it to the transgressors who spent it on a forbidden purpose, nor is it lawful for the repentant person to keep it. Instead, it is to be given away in charity and spent for the welfare of the Muslims, just as Aḥmad ruled concerning the wage of the porter who carried wine.