Is it permissible to target mosques for selling or marketing devices, or to utilize one's relationship with the imam and muezzin to offer a company's services? And is this considered among the worldly affairs that are not permissible in the houses of Allah? And does this diminish brotherhood for the sake of Allah and sincerity?

Mosques are not places for marketing and selling; they must be kept free of anything for which they were not built, namely the remembrance of Allah and prayer. Selling and buying in the mosque is disliked by the majority of scholars, and some scholars have deemed it forbidden.

The prohibition of selling and buying in the mosque has been reported in several prophetic hadiths. Some scholars view this prohibition as indicating dislike (karahah), while others consider it to be a prohibition (tahrim).

It is not permissible for someone in i'tikaf (spiritual retreat) to sell or buy inside the mosque. However, if it is done outside the mosque, near the door, there is no harm in it. As for advertising worldly matters inside the mosque, it is not permissible. However, it is permissible to advertise acts of obedience, such as Hajj and Umrah.