Musannaf Ibn Abi Shayba 18:1183

Abu Bakr narrated to us, he said: Muhammad bin Bakr narrated to us, from Ibn Jurayj, he said: Ibn Shihab said to me: "There is no *qasamah* (oath-taking procedure for homicide) in the case of a slave, nor is *qasamah* returned by him. It is only [applicable to] prices, like the form of a right that is claimed."