The Messenger of Allah ﷺ used to attack the enemy when it was dawn. He would listen to the Adhan; so if he heard an Adhan, he stopped, otherwise made an attack. Once on hearing a man say: Allah is the Greatest, Allah is the Greatest, the Messenger of Allah ﷺ remarked: He is following al-Fitra (al-Islam). Then hearing him say: I testify that there is no god but Allah. there is no god but Allah, the Messenger of Allah ﷺ said: You have come out of the Fire (of Hell). They looked at him and found that he was a goat herd.  

كَانَ رَسُولُ اللَّهِ ﷺ يُغِيرُ إِذَا طَلَعَ الْفَجْرُ وَكَانَ يَسْتَمِعُ الأَذَانَ فَإِنْ سَمِعَ أَذَانًا أَمْسَكَ وَإِلاَّ أَغَارَ فَسَمِعَ رَجُلاً يَقُولُ اللَّهُ أَكْبَرُ اللَّهُ أَكْبَرُ فَقَالَ رَسُولُ اللَّهِ ﷺ عَلَى الْفِطْرَةِ ثُمَّ قَالَ أَشْهَدُ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ أَشْهَدُ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ فَقَالَ رَسُولُ اللَّهِ ﷺ خَرَجْتَ مِنَ النَّارِ فَنَظَرُوا فَإِذَا هُوَ رَاعِي مِعْزًى