Is it permissible to speak about worldly matters, or to exchange greetings and shake hands in the mosque during the Adhan?

This hadith warns against sitting in mosques to discuss worldly matters, because the mosque was built for the worship of Allah. Upon hearing the adhan, one should repeat what the muezzin says, send blessings upon the Prophet, and ask Allah to grant him al-Waseelah, due to the reward in doing so. There is no harm in greeting and shaking hands in the mosque. A Muslim must be careful not to harm those praying, those reciting the Quran, or those remembering Allah. Speaking about worldly matters in the mosque is blameworthy and forbidden because it causes disturbance, and even if the speech is Quranic, it should not be uttered loudly.