Musannaf Ibn Abi Shayba 1:1743

Ibn Fudayl and Waki’ narrated to us, from Mis’ar, from ‘Umayr ibn Sa’d, who said: I was sitting in a gathering in which ‘Ammar ibn Yasir was present. He was asked about touching the penis during prayer. He said: "It is nothing but a piece of you, and your palm has a place other than it."