When you hear the Adhan, you should repeat the same words as the mu’adhdhin pronounces. (Using translation from Abū Dāʾūd 522)  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ «إِذَا سَمِعْتُمُ الْمُؤَذِّنَ فَقُولُوا مِثْلَ مَا يَقُولُ»  

[Machine] "Indeed, Muhammad is the Messenger of Allah. He said, and I bear witness that Muhammad is the Messenger of Allah. Yahya informed me that some of our companions told him that when he said 'Come to prayer,' he said, 'There is no power or strength except with Allah.' Then Muawiya said, 'Thus I heard your Prophet say."  

أَنَّ مُحَمَّدًا رَسُولُ اللَّهِ قَالَ وَأَنَا أَشْهَدُ أَنَّ مُحَمَّدًا رَسُولُ اللَّهِ قَالَ يَحْيَى وَأَخْبَرَنِي بَعْضُ أَصْحَابِنَا أَنَّهُ لَمَّا قَالَ حَيَّ عَلَى الصَّلَاةِ قَالَ لَا حَوْلَ وَلَا قُوَّةَ إِلَّا بِاللَّهِ ثُمَّ قَالَ مُعَاوِيَةُ هكذا سَمِعْتُ نَبِيَّكُمْ يَقُولُ  

"The Messenger of Allah ﷺ taught me the Adhan and said: 'Allahu Akbar, Allahu akbar, Allahu Akbar, Allahu Akbar; Ashhadu an la ilaha illallah, Ashhadu an la ilaha illallah; Ashhadu anna Muhammadan Rasulallah, Ashhadu anna Muhammadan Rasulallah (Allah is the Greatest,Allah is the Greatest, Allah is the Greatest, Allah is the Greatest; I bear witness that there is none worthy of worship except Allah, I bear witness that there is none worthy of worship except Allah; I bear witness that Muhammad is the Messenger Allah,I bear witness that Muhammad is the Messenger Allah)'. Then he repeated it and said: 'Ashhadu an la ilaha illallah, Ashhadu an la ilaha illallah; Ashhadu anna Muhammadan Rasulallah, Ashhadu anna Muhammadan Rasulallah; Hayya 'alas-salah, Hayya 'ala-salah; Hayya 'alal-falah Hayya 'alal-falah; Allahu Akbar, Allahu Akbar; La ilaha ill-Allah (I bear witness that there is none worthy of worship except Allah, I bear witness that there is none worthy of worship except Allah; I bear witness that Muhammad is the Messenger of Allah, I bear witness that Muhammad is the Messenger of Allah; Come to prayer, come to prayer; come to prosperity, come to prosperity; Allah is the Greatest, Allah is the Greatest; there is none worthy of worship except Allah).'" (Using translation from Nasāʾī 631)   

أَنْ لَا إِلَهَ إِلَّا اللَّهُ ثُمَّ أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللَّهُ فَقَالَ الْمُؤَذِّنُ أَشْهَدُ أَنَّ مُحَمَّدًا رَسُولُ اللَّهِ أَشْهَدُ أَنَّ مُحَمَّدًا رَسُولُ اللَّهِ فَقَالَ مُعَاوِيَةُ أَشْهَدُ أَنَّ مُحَمَّدًا رَسُولُ اللَّهِ أَشْهَدُ أَنَّ مُحَمَّدًا رَسُولُ اللَّهِ فَقَالَ الْمُؤَذِّنُ حَيَّ عَلَى الصَّلَاةِ حَيَّ عَلَى الصَّلَاةِ فَقَالَ لَا حَوْلَ وَلَا قُوَّةَ إِلَّا بِاللَّهِ فَقَالَ الْمُؤَذِّنُ حَيَّ عَلَى الْفَلَاحِ حَيَّ عَلَى الْفَلَاحِ فَقَالَ لَا حَوْلَ وَلَا قُوَّةَ إِلَّا بِاللَّهِ فَقَالَ الْمُؤَذِّنُ اللَّهُ أَكْبَرُ اللَّهُ أَكْبَرُ لَا إِلَهَ إِلَّا اللَّهُ فَقَالَ اللَّهُ أَكْبَرُ اللَّهُ أَكْبَرُ لَا إِلَهَ إِلَّا اللَّهُ ثُمَّ قَالَ هَكَذَا فَعَلَ رَسُولُ اللَّهِ ﷺ