After the age of Rama came the age of Lord Krishna, and Hanuman gladly offered his services to Krishna who was, after all, none other than Rama himself since both are incarnations of Lord Vishnu.
Lord Krishna had asked Narada to find Hanuman, since Hanuman would have no idea of who Krishna was, but was closely acquainted with Narada.
Narada is the lute player of the gods; Tumburu is the lute player of the Gandharvas. Once they decided to test each other's excellence, but since they were the leading musicians of their respective groups, there was no one left to judge their skills. Somebody suggested that they should go to Hanuman for a final, impartial judgment.
Hanuman received them well and said, "The only way I can decide is to put you both through a test." Narada and Tumburu agreed. Then Hanuman said, "You must first listen to my singing. Only if I am better than both of you can I be your judge."
Hanuman started chanting the name of Rama in a wonderful raga, a melody unknown to both the candidates. The impact of this singing was such that the mountains themselves were moved and turned into streams of molten rock. Suddenly, Hanuman snatched the lutes of Narada and Tumburu and cast them into that molten stream and stopped singing. The flow of molten rock also froze, trapping the lutes. Hanuman then said, "Whoever can reclaim his lute from the frozen lava is, without doubt, the better musician."
Both Narada and Tumburu stood with heads bowed. They knew this was a task beyond their skills.
Hanuman began to sing again and, when the molten rock began to flow, he plucked the lutes out of the stream.
Hanuman said, "The duty of a devotee is to live for God, not for personal glory. Music is meant to express the divine spirit, the song of the soul. When it is done as a competition, it loses the spirit." Narada, the great devotee of Hari, and Tumburu, who sings of love, realized their error. They both acknowledged Hanuman as the supreme musician and returned to their respective abodes.
When Narada brought Hanuman to Krishna, Hanuman saw Krishna in his four-armed form and Lakshmi in the form of Krishna's wife, Rukmini. He saluted them respectfully, but not seeing his own Lord Rama, he bowed his head.
The inner-dwelling and inner-knowing Lord Krishna understood and said: "Hanuman. Look again."
Raising his head, Hanuman beheld the form of Lord Rama holding his bow and arrow, standing with Mother Sita. Choked with emotion, Hanuman fell at their feet, and often spent time serving the Krishna form of Rama..

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