Musannaf Ibn Abi Shayba 18:90

Abu Bakr narrated to us, he said: Zayd ibn al-Hubab narrated to us, from Sufyan, from Malik ibn Anas, from Yazid ibn Abdullah ibn Qusayt, from Sa'id ibn al-Musayyib: That Umar and Uthman judged regarding the *multa'ah*—and it is the *samhaq* (a wound that reaches the thin membrane covering the bone)—to be half the [blood money] of the *mudihah* (a wound that exposes the bone).