Mishkat al-Masabih 19 Jihad كتاب الجهاد 126

وَعَن أبي ثعلبَةَ الخُشَنيِّ قَالَ: كَانَ النَّاسُ إِذَا نَزَلُوا مَنْزِلًا تَفَرَّقُوا فِي الشِّعَابِ وَالْأَوْدِيَةِ فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِنَّ تَفَرُّقَكُمْ فِي هَذِهِ الشِّعَابِ وَالْأَوْدِيَةِ إِنَّمَا ذَلِكُمْ مِنَ الشَّيْطَانِ» . فَلَمْ يَنْزِلُوا بَعْدَ ذَلِكَ مَنْزِلًا إِلَّا انْضَمَّ بَعْضُهُمْ إِلَى بَعْضٍ حَتَّى يُقَالَ: لَوْ بُسِطَ عَلَيْهِمْ ثوبٌ لعمَّهم. رَوَاهُ أَبُو دَاوُد

Abu Tha’laba al-Khushani said that when the people encamped they scattered in the glens and wadis , but when God’s Messenger said, “Your scattering in these glens and wadis is only of the devil,” they afterwards kept close together when they encamped to such an extent that it used to be said that if a cloth were spread over them it would cover them all. Abu Dawud transmitted it.