Abu Sa'id Al-Khudri (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) said, "When you hear the Mu'adhdhin (pronouncing the call to Salat), repeat after him what he says."[Al-Bukhari and Muslim].
App reference: Book 9, Hadith 48
Arabic/English book reference: Book 9, Hadith 1038