father's tree branch
A farmer had three sons who were always arguing. One day, the farmer called his sons and said, sticking out a small branch.
"Try to break this branch."

The sons broke the branches lightly. Then the farmer said, this time, tying the branches together.
"Now break this bundle."

No matter how hard they tried, they couldn't break the bundle of branches.

The farmer spoke quietly.
"If you are separated from each other, you will break as easily as these little branches. But if you join forces, no matter how strong your opponent will be able to defeat you."

Since that day, the sons have lived happy lives, understanding and cooperating with each other.