Jamaat Salaah and Imaamat

Making a second jamaat in the masjid

Q: I have read a few times that men should not join the second and third jamaats in the Masjid. 

In the UK, many of the Masajid are very small, serving a large number or Muslims. However, in recent years they have introduced second and third jamaats to avoid people praying on the pavement which is used by everyone public. 

Is it still the case that instead of joining the second jamaat, men should pray alone in the Masjid?

Children standing in the adults' saffs if they are misbehaving

Q: Is it correct for a person to keep his sons behind him in the masjid - away from other children as these children are causing a disturbance in the back. Some children hit others. 

What will be the correct age to bring children to the masjid? Any guidelines regarding the children's saffs as some mention that the children can stand in the adults' saffs if they are misbehaving. 

Please clarify with guidelines for our masaajid.

Moving one saff back for an Aalim to stand in the first saff for salaah

Q: When we are in the masjid and iqaamah has already started, sometimes a person in the first row moves back to make space if another learned Maulana arrives, even though there are already a few learned Ulama present in the first row. 

Should we move from our place to give space to a Maulana at that time, or should we remain focused and avoid movement so we can prepare ourselves to stand before Allah? What is the correct adab according to the sunnah?