What is the authenticity of the Hadith: "Whoever answers the Muezzin and says what he says will have the reward of a million good deeds"?

It is Sunnah (definition) for the Muslim to repeat after the Mu'adhdhin (caller to prayer), saying what the Mu'adhdhin says, based on the Prophet's (peace be upon him) saying: "When you hear the call (to prayer), say what the Mu'adhdhin says," and his saying: "Say as they say, and when you finish, ask and you shall be given." However, for the two Hay'alatayn (Hayya 'ala al-Salah (definition) - hasten to the prayer; Hayya 'ala al-Falah - hasten to success), the one repeating should say: "There is no might nor power except with Allah." As for the narration mentioned in the question, it has no origin in the books of Ahl al-Sunnah, indicating that it is a fabricated narration with no basis.