Sayyiduna Jabir bin Samurah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) came out to the rows and said: "Will you not form rows as the angels form rows before their Lord?" The Companions (may Allah be pleased with them) asked: How do the angels form rows before Allah? He (peace and blessings be upon him) said: "They first complete the front rows, and they close up the rows."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5189