Musannaf Ibn Abi Shayba 1:1745

Mulaazim ibn 'Amr narrated to us, from 'Abdullah ibn Badr, from Qays ibn Talq, from his father, Talq ibn 'Ali, who said: We went out as a delegation until we arrived at the Messenger of Allah, may Allah bless him and grant him peace. We pledged allegiance to him and prayed with him. Then a man came and said: "O Messenger of Allah, what is your opinion regarding touching the penis during prayer?" He said: "Is it anything but a piece or a morsel of you?"