What is said after the muezzin's call "Prayer is better than sleep," with proof?

It is recommended for the one who hears the Adhan to repeat what the Muezzin says, except for "Hayya 'ala as-Salah" (Hasten to prayer) and "Hayya 'ala al-Falah" (Hasten to success), where one should say "La hawla wa la quwwata illa billah" (There is no might or power except with Allah). And upon hearing "As-salatu khairun min an-nawm" (Prayer is better than sleep) in the Fajr Adhan, it is recommended for the listener to repeat it, "As-salatu khairun min an-nawm," due to the generality of the Hadith: "When you hear the Muezzin, then say as he says." As for what is mentioned about saying "Sadaqta wa bararta" (You have spoken the truth and acted righteously), there is no evidence for it, and it is a preference not based on the Sunnah.