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]. (RU)
App reference (RU): Book 9, Hadith 48 (RU)
Arabic/English book reference (RU): Book 9, Hadith 1038 (RU)