Once Arjuna decided to go on a pilgrimage to all the holy places in India. A Brahmin youth accompanied him on the pilgrimage. When they reached Ramesh-waram, the Brahmin turned to Arjuna to say, ?Do you know this is the place where Lord Ram and his monkey brigade build a bridge of arrows to connect to Sri Lanka??
Arjuna asked, ?But why did Lord Ram need the help of monkey brigade? Surely he could have built a bridge by himself.?
The Brahmin did not reply, but Hanuman, who was eavesdropping, heard it and said, ?Because the weight of the monkeys could have broken the bridge.?
Arjuna was not satisfied with the reply and asked how it was possible. Hanuman replied, ?I challenge you. You can build a bridge of arrows but it will not bear my weight.?
Arjuna took up the wager and said that if he lost, he would jump into a fire. He took out his quiver and pulled out arrows, which had been given to him by Agnideva. By shooting the arrows, Arjuna build a bridge and asked Hanuman to step on it. As soon as Hanuman did so, the bridge collapsed. Arjuna tried many times to build a strong bridge but every time the bridge collapsed. So Arjuna lit a fire to prepare to jump into it. A young boy came near Arjuna and stopped him from jumping in by saying, ?Nobody was witness to your wager. Build the bridge again and Hanuman won'tbe able to break it.?
Again Arjuna created a bridge out of his arrows and asked Hanuman to walk across it. Hanuman stepped on it and jumped hard but still the bridge did not collapse. He was surprised and wondered, ?What'swrong with me? Why am I feeling so weak as if all my strength is ebbing away. I think I must take large form that I had done when I had gone in search of Sitaji?. So he grew taller and larger till he was as huge as a mountain. Now he jumped again on the bridge but the bridge remained intact. On seeing this, Arjuna thought to himself, ?Since the bridge did not collapse this time, it means that this Brahmin boy must be Lord Krishna himself who has come to my rescue.?
Hanuman said to himself, ?The fact that despite making myself acquire such huge proportions, the bridge did not collapse, means that this Brahmin boy must be Lord Ram who has come to help him.?
Thinking thus, both Arjuna and Hanuman fell at the young Brahmin'sfeet. It was then that the Brahmin boy became Lord Vishnu and announced, ?Arjuna, you had forgotten to be humble and become proud of your strength. And Hanuman, you started thinking too highly of yourself and your strength. In punishment, you will now serve as Arjun'sflagstaff.?
Since that day Hanuman is shown as Arjun'sflagstaff.