Musannaf Ibn Abi Shayba 18:351

Abu Bakr narrated to us, he said: Abd al-Rahim narrated to us, from Muhammad ibn Ishaq, from Makhul, and from Ash'ath, from al-Zuhri, that the Prophet, may God bless him and grant him peace, decreed for the *ja'ifah* (a wound that reaches the body cavity) one-third of the blood money.