What is the ruling of Islamic law on the commission that my husband receives as a tour guide, which he considers to be a large percentage, knowing that leaving it would expose him to dismissal, and that this practice is prevalent in all tourism companies?

It is not permissible to work as a tour guide except under specific Sharia-compliant conditions. The ruling on receiving commission is based on the permissibility of the work itself. If the commission is for guiding to the purchase of prohibited items such as statues, alcohol, and musical instruments, then it is forbidden to take it, except in cases of necessity. However, if it is for guiding to the sale of permissible items, then it is permissible by mutual consent.