Rules regarding a Masjid

909. It is Haraam to make the floor, roof, ceiling and inner walls of a Masjid Najis, and as and when a person comes to know that any of these parts has become Najis, he should immediately make it Pak. And the recommended precaution is that the outer part of the wall of a Masjid, too, should not be made Najis.
And if it becomes Najis, it is not obligatory to remove the Najasat. But if someone makes it Najis to violate its sanctity, that act is Haraam, and the Najasat should be removed.