Why is if Not Waajib (compulsory) for the people present in the Masjid to Reply to the Adhaan?

Q: Salaah-6: Although it is Waajib (compulsory) for a person to reply to the Adhaan and Iqaamah, why is this not compulsory for the person present in the Masjid?

Answer: While some Ulema are of the opinion that replying to the Adhaan and Iqaamah is Mustahab, others states that it is Waajib (compulsory). The best is to say that while physically replying (by going to the Masjid for salaah) is Waajib (compulsory), verbally replying is Mustahab. Those present in the Masjid have only the verbal reply to give, which is Mustahab. And Allaah Knows best what is most correct.

Fatawa Rahimiyyah vol.2