Sahih Muslim Book - 4, Hadith - 972

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ إِدْرِيسَ وَأَبُو مُعَاوِيَةَ وَوَكِيعٌ عَنْ الْأَعْمَشِ عَنْ عُمَارَةَ بْنِ عُمَيْرٍ التَّيْمِيِّ عَنْ أَبِي مَعْمَرٍ عَنْ أَبِي مَسْعُودٍ قَالَ كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَمْسَحُ مَنَاكِبَنَا فِي الصَّلَاةِ وَيَقُولُ اسْتَوُوا وَلَا تَخْتَلِفُوا فَتَخْتَلِفَ قُلُوبُكُمْ لِيَلِنِي مِنْكُمْ أُولُو الْأَحْلَامِ وَالنُّهَى ثُمَّ الَّذِينَ يَلُونَهُمْ ثُمَّ الَّذِينَ يَلُونَهُمْ. قَالَ أَبُو مَسْعُودٍ فَأَنْتُمْ الْيَوْمَ أَشَدُّ اخْتِلَافًا.

It was narrated that Abu Mas'ud said: "The Messenger of Allah (s.a.w) used to touch our shoulders when we were standing for prayers and he would say: 'Make the rows straight and do not differ, lest your hearts differ. Let those who are most wise and possessing intellect be closest to me, then those who come after them, then those who come after them."' Abu Mas'ud said: "But today there is a great deal of discord among you."