Musannaf Ibn Abi Shayba 24:168

Ibn Fudayl narrated to us, from ‘Ata’ ibn al-Sa’ib, from Maysarah, who said: A young boy or a young girl—from among those whom al-Hajjaj was sending out to the Sawad—would pass by him. He would say, "Who is your Lord?" and the boy would say, "Allah." He would say, "Who is your Prophet?" and the boy would say, "Muhammad, may Allah bless him and grant him peace." He said: Then he would say, "By Allah, besides whom there is no god, I do not find anyone fighting al-Hajjaj except that I would fight alongside him against al-Hajjaj."