What is the ruling on reserving a place in the mosque, and is it permissible to reserve a place when one needs to relieve oneself or bring a sick person?

The most correct opinion is that it is forbidden to reserve a place in the mosque with a prayer rug or similar item while its owner is absent, because that is an usurpation of the spot and a prevention of Muslims from what Allah has commanded them to do, which is prayer. It is obligatory to remove these prayer rugs and enable people to use their places. An exception to this is if the one who reserved the spot is still inside the mosque, or if he left for a need and returned shortly, or if his excuse continued, then he has more right to his place.