Introduction to the red stone carving: On the back of the red stone carving is engraved "Never forget the old master, understand the coming and going, he is a true husband. You should all follow suit." Inscribed for calligrapher Zhang Zili. This is what Cao Cao said when he learned of Guan Yu's resignation. Cao Cao asked the generals to learn from Guan Yu's "true husband" qualities. This also shows that Cao Cao cherishes talents and keeps his promises.