On one occasion, Hazrat Abu Musa Ash'ari (may Allah be pleased with him) led his companions in prayer, then while mentioning a hadith, he said that once the Noble Prophet (peace and blessings be upon him) delivered a sermon to us and, while explaining the Sunnahs, taught us the method of prayer and said: When you pray, straighten your rows and one man from among you should become the imam... Then he mentioned the complete hadith.