Umar ibn al-Khattab reported: The Messenger of Allah, peace and blessings be upon him, said, “When the caller to prayer says, ‘Allah is the greatest, Allah is the greatest,’ then let one of you say, ‘Allah is the greatest, Allah is the greatest.’ Then he says, ‘I testify there is no God but Allah,’ one says, ‘I testify there is no God but Allah.’ Then he says, ‘I testify Muhammad is the Messenger of Allah,’ one says, ‘I testify Muhammad is the Messenger of Allah.’ Then he says, ‘Come to prayer,’ one says, ‘There is no movement or might but in Allah.’ Then he says, ‘Come to salvation,’ one says, ‘There is no movement or might but in Allah.’ Then he says, ‘Allah is the greatest, Allah is the greatest,’ one says, ‘Allah is the greatest, Allah is the greatest.’ Then he says, ‘There is no God but Allah,’ one says, ‘There is no God but Allah,’ from his heart and he will enter Paradise.”
Source: Ṣaḥīḥ Muslim 385
Grade: Sahih (authentic) according to Muslim
عَنْ عُمَرَ بْنِ الْخَطَّابِ قَالَ قَالَ رَسُولُ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ إِذَا قَالَ الْمُؤَذِّنُ اللهُ أَكْبَرُ اللهُ أَكْبَرُ فَقَالَ أَحَدُكُمْ اللهُ أَكْبَرُ اللهُ أَكْبَرُ ثُمَّ قَالَ أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللهُ قَالَ أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللهُ ثُمَّ قَالَ أَشْهَدُ أَنَّ مُحَمَّدًا رَسُولُ اللهِ قَالَ أَشْهَدُ أَنَّ مُحَمَّدًا رَسُولُ اللهِ ثُمَّ قَالَ حَيَّ عَلَى الصَّلَاةِ قَالَ لَا حَوْلَ وَلَا قُوَّةَ إِلَّا بِاللهِ ثُمَّ قَالَ حَيَّ عَلَى الْفَلَاحِ قَالَ لَا حَوْلَ وَلَا قُوَّةَ إِلَّا بِاللهِ ثُمَّ قَالَ اللهُ أَكْبَرُ اللهُ أَكْبَرُ قَالَ اللهُ أَكْبَرُ اللهُ أَكْبَرُ ثُمَّ قَالَ لَا إِلَهَ إِلَّا اللهُ قَالَ لَا إِلَهَ إِلَّا اللهُ مِنْ قَلْبِهِ دَخَلَ الْجَنَّةَ
385 باب استحباب القول مثل قول المؤذن لمن سمعه ثم يصلي على النبي صلى الله عليه وسلم ثم يسأل الله له الوسيلة