Returning home from one of the holy journeys, Nanak stopped at Syedpur in western Punjab. This was the time of the invasion of the first Mughal emperor Babur. War, killing, loot, destruction was happening all around and India was passing through a period of turmoil. Besides warriors, innocent people and children were being massacred. Human life had no value.
Guru Nanak was aggrieved to see all this. Mardana was also moved by the killings, particularly of innocent people. One day while they were walking together, Mardana asked, "Why were so many innocent people put to death along with those few who were guilty?"
Guru Nanak looked at him then turned around. He came to a banyan tree. He asked Mardana to wait for him.
He said that he would return after a while with an appropriate answer to his question. Mardana sat there waiting.
It so happened that there was an anthill where Mardana was sitting. After a while, Mardana was stung by an ant. The sting was painful. Mardana was angry. He began thumping the ants with his feet. He killed many ants, destroyed the anthill and was still busy killing them when Nanak returned and asked, "What are you doing?"
"I am killing ants," answered Mardana.
"Why are you killing them?"
"One of them has bitten me."
"But you are killing the innocent ones." Guru Nanak was calm.
Suddenly, Mardana realised that in anger he was committing a crime. He looked up towards the Guru who said, "Now do you realise why many innocent persons are killed though only a few are guilty."
Mardana had already realised it.