It is narrated from Hazrat Bara (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "Keep the rows straight and do not let 'Hadhaf' like children stand in the rows." Someone asked, "O Messenger of Allah! What is meant by 'Hadhaf' like children?" He replied, "Those black, beardless ones who are in the land of Yemen."