Using loudspeakers in the mosque for worldly matters
What is the ruling for using items belonging to mosques for personal interests in return for a fee, that according to those who support this opinion, is to be spent on the mosque? These include using loudspeakers for publicizing merchandise, their prices and places where they are sold and for announcing students' results.
It is established in Islamic law that mosques are dedicated to the worship of Allah and to Muslims' public interests without aiming to make a profit.
Based on this, it is impermissible to use loudspeakers belonging to the mosque for publicizing merchandise or announcing students' results in return for a fee.
The Prophet [pbuh] said: "If you see someone selling or buying in the Mosque, say: 'May Allah not render your business profitable.' And if you hear someone in the mosque announcing some object which he has lost, say: 'May Allah not return your lost item'. " [Reported by al-Nisa`i and al-Tirmidhi. Al-Tirmidhi declared it fair].
The above answers the question and Allah Almighty knows best.