This is an interesting folk tale from Africa.
Once upon a time, there lived a wise man by the name of Mamad. He never lied. All the people in the land, even the ones who lived 20 days away, knew about him.
Eventually, the king too came to hear about Mamad and ordered his subjects to bring him to the palace. He looked at the wise man and asked: “Mamad, is it true that you have never lied?”
“Yes king, it’s true,” replied Mamad.
“And you will never lie in your life?” asked the king
“I’m sure of that,” said Mamad.
“Okay, tell the truth, but be careful! The lie is cunning and it gets on the tongue easily,” said the king and sent him back.
Several days passed and the king called Mamad once again. This time there was a big crowd; the king was about to go hunting. He held his horse by the mane, and his left foot was already on the stirrup. And he ordered Mamad:
“Go to my summer palace and tell the queen that I will be with her for lunch. Tell her to prepare a big feast. You will have lunch with me then.”
Mamad bowed and went to the queen. Then the king laughed and said: “I won’t go hunting today nor will I go to the summer palace for lunch. And now Mamad will lie to the queen. Tomorrow, we shall have a good laugh at him.”
But the wise Mamad went to the palace, met the queen, and said: “Maybe you should prepare a big feast for lunch today, or maybe tomorrow, and maybe you shouldn’t. Maybe the king will come by this noon, or tomorrow, or maybe he won’t.”
“Tell me, will he come, or won’t he?” asked the queen.
“I don’t know whether he put his right foot on the stirrup, or he put back his left foot on the ground after I left,” said Mamad.
The next day, everyone waited for the king at the palace. He came and said to the queen: “The wise Mamad, who never lies, lied to you yesterday.”
The queen narrated to him what Mamad told her. And the king realised that a wise man never lies, and says only that which he sees with his own eyes.