"Use your tact to protect yourself from destruction".
Kharanakhara was a lion who ruled over a certain part of a jungle.
One day, he could not prey upon a single animal after wandering around the jungle in search of food. It was almost sunset, and the lion started returning in spite of being very hungry.
On his way, he saw a big cave, and thought to himself, "It is for sure that some animal must be living in this big cave. Such a nice cave cannot be un-inhabitated. At sunset, whatever animal lives here is bound to return. I shall hide inside the cave and wait for my dinner to arrive."
The cave was the home to a jackal, who arrived a while after the lion had hidden himself inside. While entering he noticed the footprints of the lion leading into the cave, but could not find any footprint coming out.
He thought, "If a lion is indeed entered, I will be dead as soon as I enter. But, how can I be sure? There is no reason for me to stay away from my home if there is no lion inside. I must find out a way to confirm if the lion is still inside."
The jackal thought of a plan, and standing in front of the cave, began to shout, "Hello Cave! Hello Cave! Can I come inside?"
For some moment, he waited in silence and shouted again, "Hello Cave! Have you forgotten our understanding of all these years? I always wait for your reply before I enter. Why are you silent today? I shall then go to some other cave if you do not reply."
On hearing this, the lion thought, "The cave must reply to the jackal when he returns at sunset. It is because I am inside that the cave is not replying today. I must invite on behalf of the cave, or the jackal will go away."
So, the lion replied from inside the cave, "Hello Jackal, you may enter. It is safe inside."
The reply was even more frightening due to the echo from the walls of the cave. The jackal at once knew that the lion was waiting for him to enter and make a meal out of him. He ran off, as fast as he could and saved himself.
The wise indeed say: Use your tact to protect yourself from destruction.