Ruling 886. It is unlawful to make impure a mosque’s floor, ceiling, roof, and inside walls, as well as fixtures and fittings that are deemed to be part of the building, such as doors and windows.

Whoever finds out that it has become impure must immediately purify it. The recommended precaution is that the outside walls of the mosque should not be made impure either, but if they become impure, it is not necessary to purify them. However, if making the outside walls of a mosque impure amounts to disrespecting the mosque, it would, of course, be unlawful and make it necessary to purify them to the extent that it would no longer be considered disrespectful.

Ruling 887. If someone cannot make a mosque pure or needs help to do so but does not find it, it is not obligatory for him to make it pure. However, in the event that he knows that if he informs someone else it would be done, then, if leaving the impurity as it is would cause disrespect to the mosque, he must inform the other person.

Ruling 888. If a place in a mosque becomes impure and it cannot be made pure without digging it up or demolishing it, the impure place must be dug up or demolished provided that it is only a little area, or if rectifying the disrespect caused to the mosque is dependent on digging up or demolishing a large area; otherwise, demolishing it is problematic [i.e. based on obligatory precaution, it must not be demolished]. Furthermore, it is not obligatory to fill the place that has been dug up or rebuild the place that has been demolished. However, if something like a brick of the mosque becomes impure, then after it has been washed, it must be put back in its original position, if possible.

Ruling 889. If someone usurps a mosque and builds a house or something similar in its place, or if it becomes ruined to the extent that it can no longer be called a mosque, then making it impure is not unlawful, nor is it obligatory to purify it.

Ruling 890. It is unlawful to make the shrines of the Infallible Imams (ʿA) impure. If one of the shrines becomes impure, in the event that it remaining impure is disrespectful, it is obligatory to make it pure. In fact, the recommended precaution is that even if it is not disrespectful, it should be made pure.

Ruling 891. If the ḥaṣīr[1] or carpet of a mosque becomes impure, it must be washed; and if cutting out the impure part is better, it must be cut out. However, cutting out a considerable amount, or making it pure by causing damage to it, is problematic [i.e. based on obligatory precaution, it must not be done], unless leaving it causes disrespect.

Ruling 892. Taking something that is an intrinsic impurity, or something that has become impure by secondary means (mutanajjis), into a mosque is unlawful if it causes disrespect to the mosque. In fact, the recommended precaution is that even if it is not disrespectful, an intrinsic impurity should not be taken into a mosque unless it is something that naturally comes in with a person when he enters a mosque, such as the blood of a wound that is on his body or clothing.

Ruling 893. If for the purposes of holding mourning ceremonies a mosque is draped in curtains and covered in rugs and black cloth, and if utensils for serving tea are brought into it, then as long as these actions do not damage the mosque or obstruct the performing of prayers in it, there is no problem.

Ruling 894. The obligatory precaution is that a mosque must not be decorated with gold. And the recommended precaution is that it should not be decorated with things that have the form of a human being, an animal, or anything else that has a soul.

Ruling 895. Even if a mosque is ruined, it is not permitted to sell it or make it part of another property or road.

Ruling 896. Selling the doors, windows, and other things of a mosque is unlawful; and if a mosque becomes ruined, these things must be used solely for the renovation of the same mosque. In the event that they are of no use to that mosque, they must be used in another mosque. If they are of no use to other mosques, they can be sold and the proceeds must be used solely for the renovation of that same mosque, if possible. If this is not possible either, the proceeds must be used on the renovation of another mosque.

Ruling 897. It is recommended to build a mosque and to renovate one that is close to ruin. If a mosque is ruined to the extent that it is not possible to renovate it, it can be demolished and rebuilt. In fact, to meet the needs of the people, a mosque that is not ruined can be demolished and a bigger mosque built.

Ruling 898. It is recommended for one to clean a mosque and to turn on its lights. For someone who wants to visit a mosque, it is recommended to apply perfume, wear clean and good clothes, and ensure that the soles of his shoes do not contain any impurity. When entering a mosque, it is recommended for one to place his right foot in first, and when leaving it, to put his left foot out first. It is also recommended that one come to the mosque earlier than everyone else and leave it later than everyone else.

Ruling 899. It is recommended that when a person enters a mosque, he should perform a two rakʿah prayer with the intention of saluting (taḥiyyah) and respecting (iḥtirām) the mosque; and if he performs an obligatory prayer or another recommended prayer, it is sufficient.

Ruling 900. The following are disapproved for a person to do in a mosque: sleep (unless he is compelled to), talk about worldly affairs, engage in craft, recite poetry (unless it exhorts people to good), and similar things. It is also disapproved to discharge nasal mucus, saliva, and phlegm in a mosque; in fact, this is unlawful in some cases. Furthermore, it is disapproved to look for something lost or raise one’s voice in a mosque; however, there is no problem in raising one’s voice for adhān.

Ruling 901. It is disapproved to give access to an insane person to enter a mosque, and similarly, to a child if it causes trouble for those performing prayers there or there is a probability that the child would make the mosque impure. Apart from these two reasons, there is no problem in allowing a child to enter a mosque; indeed, sometimes it is preferable to do so. Furthermore, if someone has eaten onions, garlic, or something similar, and his breath would thereby annoy people, it is disapproved for him to go to a mosque.