Following Kabandha's suggestion, Rama and Laxmana came to the Rishyamooka forest where Sugreeva lived with his army of monkeys. Thinking they might be Bali's spies, Sugreeva became worried.
He ordered his loyal minister Hanuman to find out. Hanuman took the form of a Brahmin and went to the brothers. Seeing Rama he knew that he could not be a wicked spy. At once changing into his original form he asked the brothers to introduce themselves. When Rama and Laxmana told him their story, Hanuman bowed respectfully and said he was Vayu's son and also the exiled king Sugreeva's deputy. On hearing that Rama and Laxmana had come searching for Sugreeva, Hanuman said it would be an honour to help Rama to free Sita from Ravana's clutches.
He promised Rama his eternal friendship, and then taking the brothers on his sturdy shoulders he flew to Rishyamooka forest.