Musannaf Ibn Abi Shayba 35:232

Waki’ narrated to us, from Sufyan, from Husayn, from a sheikh, from Ibn Umar, that he drew his sword against a monk who had insulted the Prophet, may Allah bless him and grant him peace. He said, "We did not make a peace treaty with you on the condition that you insult our Prophet, may Allah bless him and grant him peace." And he mentioned that Abu Hanifa said, "He is not to be killed."