The ruling on locking the Masjid at night

Question :

Were the Masjids locked at night during the time of the Messenger of Allâh, and the Muslims who came to visit the sacred places put out and made to sleep outside around the wall of the Masjid?

Answer:

The Masjids were not locked in the time of the Messenger of Allâh as far as we know. The Masjids were not furnished and the people had too much fear of Allâh to do anything corrupt inside of them or defile them. However, when the Masjids are furnished and things are placed inside of them that are feared might be stolen by thieves, and the ignorance of the people is great and some of them do corrupt things in the Masjids, it is permissible for whoever is in authority to lock up whatever he sees fit of them. This is if he (the one in charge) sees some benefit in this as a means of protecting and safeguarding the Masjids due to what is inside of them, and defending them from the corruption of the foolish people. May Allah send blessings and peace upon our Prophet Muhammad.

Source:
The Permanent Committee
Fatawa Islamiyah, Vol. 3 Page 41