As the mistake was completed via the god Indra, he grants Hanuman a wish that his human body could be as strong as Indra's Vajra, Which his Vajra also can not hurt him. Coupled with Indra other gods have also granted him needs: the God Agni granted Hanuman a want https://trentonduiyn.techionblog.com/37139296/little-known-facts-about-hanuman