The conditions for establishing a masjid are the following:

1) Waqf (endowment)

i.e. The owner of that land or building which is being converted into a masjid must give up his right as owner, and establish that land or building as a religious endowment.

2) Giving adhan

3) Establishing obligatory prayer

After these conditions are fulfilled, this land or building will be considered a Masjid. Therefore, all the rulings that are specific to a masjid will now apply. Such as the prohibition of entering the masjid for a lady in her menses or a man in janaabat (major impurity).

Once a masjid is established, it can never be sold, inherited, gifted or put as collateral. The masjid will always remain as a religious endowment. This is understood from the verse below:

{ وَأَنَّ الْمَسَاجِدَ لِلَّهِ}Quran 72:18

Translation: Verily, all the masaajid belong to Allah.

The literal translation of musallah is any place where salah is offered. If a person had a specific room in their house dedicated for salah, that room would be called a musallah.

In the time we live in, we have many musallahs where jummah salah, as well as five-time prayers are established. These musallahs outwardly look just like a masjid, however, the conditions for them to be considered a masjid are not found.

We would often find that these musallahs are either rented, mortgaged, or owned by a specific individual. The condition of the musallah being a religious endowment is not found. Therefore, these musllahs will not be considered a masjid.