What is the Shariah ruling on spying on the Muslim or monitoring? Recently in our Masjid, we cam for Salat this week only to find out that 9 surveillance cameras had been install in ad around the Masjid. Some brothers have been complaining that they don't feel comfortable and a lot of talking is going on. Is there a Hadith that mentions listening to people who do not want you to hear them? And what is the general ruling on installing cameras inside the Masjid.

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. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Spying and looking for people's faults are a means to much evil and corruption.  The Prophet said: "If you look for people's faults, you spoil them, or you are about to spoil them." [Abu Daawood].  It is for this reason spying is prohibited.   Allaah Says (what means): {....And spy not}[Quran 49: 12].  Furthermore, the Prophet said: "Beware of suspicion, for suspicion is the worst of false tales.  And do not look for others' faults, or spy on them." [Al-Bukhari and Muslim]  So, among the merits of Islam is that it respects the privacy of others and prohibits revealing their privacy, as this might cause them much trouble.

Allaah Knows best.