Musannaf Ibn Abi Shayba 18:211

Abu Bakr narrated to us, he said: Muhammad ibn Bakr narrated to us, from Ibn Jurayj, he said: Sulayman ibn Musa said in the book of Umar ibn Abd al-Aziz: Whatever is cut off from the tongue, and it reaches the point of preventing all speech, then in it is the full blood money (diyah). And whatever is diminished less than that, then it is according to its proportion.