REPEAT THE CALL TO PRAYER H 1054 "When you hear the call to prayer repeat after the Caller to Prayer what he says." R 1054 Bukhari and Muslim with a chain up to Abu Sa'id Khudri who related that the Messenger of Allah, praise and peace be upon him, said this.
1038- وعن أَبي سعيد الخدري رضي الله عنه : أنَّ رسول الله صلى الله عليه وآله وسلم ، قَالَ : "إِذَا سَمِعْتُمُ النِّدَاءَ ، فَقُولُوا كَمَا يَقُولُ المُؤذِّنُ" متفقٌ عَلَيْهِ .