Musannaf Ibn Abi Shayba 19:846

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Shu’bah, who said: I asked al-Hakam and Hammad about a man who kills, then enters the Sacred Precinct (al-Haram). Hammad said: He is brought out, and the prescribed punishment (hadd) is carried out upon him. And al-Hakam said: He is not to be traded with, and he is not to be eaten with.