This is the The Prince and The Sage short story. Once, there was a wise and generous king, who had an ill-mannered son.
One day, a sage visited the king. The king welcomed him and offered him a hermitage near the palace.

One day, the king visited the hermitage and said, “My son is ill-mannered. Please change his ways so that he may be a worthy successor to the throne.”
The sage took the prince for a walk in the royal gardens. The sage pointed to a small plant and said, “Taste a leaf of this plant.”
The prince tasted a leaf and spat it out. He said, “It’s bitter! It will grow into a poisonous tree.”
Then he pulled out the plant and threw it away.
The sage said, “The subjects of your kingdom might not want you as the king. A humble person can win the hearts of everyone.”
The prince thanked the sage and changed for the better.