Musannaf Ibn Abi Shaybah

Hazrat Zaid bin Wahb narrates that Hazrat Umar bin Khattab saw a man who, after the sun had set, performed two rak'ahs before the Maghrib prayer and during them kept turning here and there. When he completed the prayer, Hazrat Umar struck him with his whip and said, "Do not turn here and there during prayer." He did not say anything to him regarding those two rak'ahs.