What is the Sharīʿah ruling on a husband allowing his first wife to impose restrictions on his second wife, based on the first wife's request, while the second wife knows that the aim is to prevent her from doing volunteer work? And is this behavior considered just among wives?

The husband must be just among his wives in providing for them, in overnight stays, and in housing. Part of good management of polygynous households is not allowing one wife to interfere in the affairs of another, because this leads to the failure of polygyny. Therefore, the first wife has no authority to interfere in the affairs of the second wife, and the husband must prevent such interference. The wife is advised to be patient and gentle with her husband when expressing disapproval, for patience, wisdom, and good companionship can resolve problems.