Musannaf Ibn Abi Shayba 19:845

Abu Bakr narrated to us, he said: Abu Mu'awiyah narrated to us, from Hajjaj, from 'Ata, from Ibn 'Umar and Ibn 'Abbas, they both said: "If we were to find the killer of our fathers in the Sacred Precinct (Haram), we would not kill him."