How to act when coming too late to prayer in Masjid
2-2-2012 | IslamWeb
Question:
Assalamu alaikum…. How do I convince a person having come late to the masjid, immediately after praying the mandatory salaat, whilst others in the front rows have not had a chance to move, starts the sunna/nafal prayers, preventing others to move out, that he is being a nuisance whilst at the same time trying to earn Allah’s pleasure. Abu Munib Al Punjabi
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad 
is His slave and Messenger.
It is better for this person to come to the prayer early rather than late. So you should explain the importance of going early to the prayer to him in a soft and gentle manner, and the merits of doing so, like being in the first row, being present at the beginning of the prayer (i.e. starting with the Imaam when he begins the prayer by saying Allaahu Akbar) and the like.
As regards this person praying the Rawaatib (confirmed supererogatory prayers connected to obligatory prayers) right after the obligatory prayer, then it is better for him to first recite the Athkaar (authentic words of remembrance of Allaah The Almighty) after the obligatory prayer in order to obtain its merit (i.e., get its reward). It is more appropriate for him to pray the Sunnah prayer at home, as the best prayer for a person with the exception of the obligatory prayer is at home as confirmed from the Prophet .
Therefore, you should explain all this to him, and clarify that he should be keen on obtaining the most reward and not miss such virtues.
However, he is not sinful for praying the Sunnah prayer in the mosque but he misses the merit of performing it at home.
If he stands to pray after the obligatory prayer (in the mosque), then he should take something as a Sutrah (an object that prevents others from passing in front of him within his praying area) in order to prevent other people passing in front of him.
For more benefit, please refer to Fatwa 106812.
Hence, you should advise him of this great Sunnah and clarify to him that the Prophet ordered the people to do so. Some scholars are of the view that it is an obligation to put the Sutrah, and some of them are of the view that it is forbidden for one to subject himself to other people passing in front of him.
In case he prays without using a Sutrah, then the people who want to pass in front of him should pass beyond the place of his prostration, which is the place of his Sutrah if he had taken it.
Allaah Knows best.