Musannaf Ibn Abi Shaybah 3563 — Straightening the row

Sayyiduna Nu'man bin Bashir (may Allah be pleased with him) said: I saw the Prophet (peace and blessings be upon him) straightening the rows the way an arrow shaft is straightened. One day he saw a man's chest sticking out of the row, and he said: "Straighten your rows, or else Allah Almighty will put aversion in your hearts towards one another."