Better be wise by the misfortunes of others than by your own.
Samos, Greece
A crust eaten in peace is better than a banquet partaken in anxiety.
Beware lest you lose the substance by grasping at the shadow.
Beware the wolf in sheep's clothing.
Example is the best lesson there is.
A wise man gets more use from his enemies than a fool from his friends.
Learn about pines from the pine, and about bamboo from the bamboo.