Musannaf Ibn Abi Shayba 19:843

Abu Bakr narrated to us, he said: Abd al-Salam ibn Harb narrated to us, from Khusayf, from Mujahid, that a man killed a man, then entered the Sacred Precinct (al-Haram). He said: He is to be seized and taken out of the Sacred Precinct, then the prescribed punishment (hadd) is to be carried out upon him, meaning execution.