Sahih Muslim 2499
Abu Musa reported that Allah's Messenger (ﷺ) said:
I recognise the voice of the Ash'arites while they recite the Qur'an as they arrive during the night and I also recognise their station from the recital of the Qur'an during the night time, although I have not seen their encampments as they encamp during the day time. And there is a person amongst them, Hakim; when he encounters the horsemen or the enemies he says to them: My friends command you to wait for them.
حَدَّثَنَا أَبُو كُرَيْبٍ، مُحَمَّدُ بْنُ الْعَلاَءِ حَدَّثَنَا أَبُو أُسَامَةَ، حَدَّثَنَا بُرَيْدٌ، عَنْ أَبِي بُرْدَةَ،
 عَنْ أَبِي مُوسَى، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏
"‏ إِنِّي لأَعْرِفُ أَصْوَاتَ رُفْقَةِ
 الأَشْعَرِيِّينَ بِالْقُرْآنِ حِينَ يَدْخُلُونَ بِاللَّيْلِ وَأَعْرِفُ مَنَازِلَهُمْ مِنْ أَصْوَاتِهِمْ بِالْقُرْآنِ بِاللَّيْلِ
 وَإِنْ كُنْتُ لَمْ أَرَ مَنَازِلَهُمْ حِينَ نَزَلُوا بِالنَّهَارِ وَمِنْهُمْ حَكِيمٌ إِذَا لَقِيَ الْخَيْلَ - أَوْ قَالَ الْعَدُوَّ
 - قَالَ لَهُمْ إِنَّ أَصْحَابِي يَأْمُرُونَكُمْ أَنْ تَنْظُرُوهُمْ ‏"‏ ‏.‏