Once Arjun was on pilgrimage and reached Rameshwaram. When he saw the setu(bridge), he wondered that why Lord Rama needed the help of vanar sena(troops of monkeys) though he himself was a great archer. This was the time when Arjun’s thought was governed by his ego and boast of him to be great archer. He found that one monkey was following him. The monkey tried to answer his doubt and said that it was not practical to built the bridge of arrows by Lord Rama because it would not able to bear the weight of huge monkey army. On hearing this Arjun laughed and challenged monkey that the bridge made by him could have bear the weight easily and if it failed to do so then he would jumped into the fire. The monkey agreed the challenge and asked Arjun to build a bridge from his arrows.Arjun with his great skills built a very strong bridge. But the moment the monkey stepped on to the bridge , it collapsed.Arjuna accepted the defeat and made a fire ready jumped into.at the very moment one Brahman who was none other than Lord Krishna visited and enquired the matter. The Brahman offered his shoulder at the foundation of bridge and asked Arjun to repeat the task. Again the bridge was built by Arjun with his arrows and when monkey set his foot , the bridge did not collapsed. Arjun was stunned. The monkey appeared in his original form of Hanuman and greet the Brahman who was Lord Krishna(an incarnation of Lord Rama).
Lord Krishna said “ Dear Hanuman!! In previous yuga you have done so much for me and carried me on your shoulder.In this yuga I came to carry you on my shoulder. Also I wanted to teach Arjun a lesson who was living with a false ego”
Arjuna went into tears and asked for forgiveness as the Lord has to came to rescue him. Lord Krishna also honoured his disciple claim of building the bridge second time.God never let HIS children down.