What is the ruling on the muezzin saying "Hayya 'ala al-Salah" (Hasten to the prayer) and "Hayya 'ala al-Falah" (Hasten to salvation) instead of "Pray in your homes" when mosques are closed due to an epidemic, and is it obligatory to respond to the call by going to the prayer or by praying at home, and what should be said upon hearing "Hayya 'ala al-Salah" when the situation necessitates "Pray in your homes"?

It is legislated for the mu'adhdhin, if unable to go to the mosque, to say in his adhan: "Pray in your homes." He may say this during the adhan after the two hay'alatayn (Hayya ‘ala as-Salah, Hayya ‘ala al-Falah), or after completing the adhan. Saying it after the adhan is preferable, so that the structure of the adhan remains in its proper form. If the mu'adhdhin does not say it, there is no sin upon him. And when responding to "Hayya ‘ala as-Salah, Hayya ‘ala al-Falah," one should say: "La hawla wa la quwwata illa billah (There is no might or power except with Allah)."