During the exile of the Pandavas, Krishna visited them to enquire about their welfare. He spent a night with them. The Pandavas had to undergo untold suffering during their exile. As Draupadi was also with them, they would keep vigil in turns for one hour each, every night. Krishna also volunteered to keep vigil for one hour.
Dharmaja wondered, "When You are the protector of the entire universe, what is the meaning in your standing sentry for an hour to protect us?" Yet he cautioned Krishna: "Krishna, beware of the devil - my brothers and I encounter it every night. On many occasions it has tried to attack us. Therefore, we pray to you not to do a turn in guard duty. You have come to enquire about our welfare. We should not put you in danger. Kindly take rest." Krishna replied, "Dharmaja, is this what you have understood of my divinity? On the one hand you extol me as the protector of the entire universe and on the other you are apprehensive that I cannot protect myself. You are worried that the demon will harm me. Rest assured that no demon can touch me. Therefore, permit me also to join you all in doing the security duty."
Having completed one-hour duty, Krishna sat on a rock and was smiling to himself. It was Arjuna's turn next. He rushed to Krishna, a bit worried that the demon might have attacked him. Seeing Krishna smiling, Arjuna fell at His feet and enquired whether he had vanquished the demon. Krishna replied, "Arjuna, I have never created demons and evil spirits. Then, how can the non-existent demons appear in the forest? The demon you are talking about is not a demon at all. It is just a reflection of the evil qualities within you such as hatred, anger and jealousy. The anger in you is manifesting as the demon. Its power is increasing in proportion to the intensity of anger in you." The evil qualities of man are the real demons troubling him today. Man is under the mistaken notion that demons exist and that they are responsible for his suffering. This is all nothing but imagination and psychological fear. Only man puts another man to suffering; there is no demon as such. There are no demons and evil spirits in this creation. Arjuna realised the truth of Krishna's words and thereafter did not encounter the demon. Arjuna was beholden to Krishna for the revelation. He fell at his feet and expressed his gratitude. Good and bad are man's own creations.