عَنْ أَنَسِ بْنِ مَالِكٍ رَضِيَ اللَّهُ عَنْهُ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ يُقْبِلُ عَلَيْنَا بِوَجْهِهِ قَبْلَ أَنْ يُكَبِّرَ فَيَقُولُ: ((تَرَاصُّوا (وَفِي رِوَايَةٍ: أَقِيمُوا صُفُوفَكُمْ وَتَرَاصُّوا) وَاعْتَدِلُوا فَإِنِّي أَرَاكُمْ مِنْ وَرَاءِ ظَهْرِي))
Sayyiduna Anas bin Malik (may Allah be pleased with him) says: Before saying the opening Takbir, the Messenger of Allah (peace and blessings be upon him) would turn towards us and say: Join together firmly (and in one narration: straighten your rows and join together), and be aligned, for indeed I see you from behind me.