Is it permissible to stipulate the recovery of the capital in a Mudarabah contract, given that the capital shares in profit and loss?

The condition stipulated by the wife to the merchant is void, because it is a form of Mudarabah, in which it is impermissible to stipulate a guarantee of the capital. Mudarabah is a partnership between the capital provider (with the capital) and the worker (with his effort and expertise). The profit is shared between them according to their agreement, and any loss is borne by the capital. The worker bears none of it, as he has already lost his effort and time. The worker's hand is that of a trustee, and he is not liable for guarantee unless there is transgression or negligence.