Even while injured, old, and ill, Guan Yu's appearance strikes fear in Wei forces

"Father, you are not strong enough to go into the battle," said Guan Ping.
"Xu Huang and I were once friends, and I know what he can do and not do. I will give him the chance to retire. If he does not take it, then I shall just slay him as a warning to the others."
Mounting his charger, Guan Yu rode out as impetuously as of yore, and the sight of the old warrior made to quake the hearts of the troops of Wei (Romance of the Three Kingdoms, Ch 76).