Musannaf Ibn Abi Shayba 3:2222

Ibn ‘Ulayyah narrated to us, from al-Jurayri, from Hayyan ibn ‘Umayr, who said: I was with Qays ibn ‘Abbad. He saw a man praying while placing his hand on his waist (mutakassiran). He said: Go to that man and say to him: "You are placing your hand in the place of the restrainer (al-zajir)."