Mischievous in his youth, Hanuman would often bother the temple priests and sages by disrupting their sacrificial ceremonies in various ways. Angered by Hanuman’s antics, they eventually cursed him to forget his powers until he was reminded of them by another.
It wasn’t until years later, when Hanuman was helping Rama search for Sita, that the knowledge of his powers were restored to him. Having discovered that Sita was being held captive across the ocean in Sri Lanka, the Vanaras wondered who among them could leap over the sea to reach Ravana’s kingdom.
Aware of his divine origin and childhood, Jambavan, an intelligent bear king who was helping the Vanaras, began describing Hanuman’s true power to all who were present. As Jambavan finished his speech — effectively ending the sages’ curse — Hanuman, remembering his prowess, stood up, and with a great roar, made his declaration to perform the task. Expanding his body to 50 times its normal height, he squatted down, and then sprang forth with immense energy.