As The mistake was performed with the god Indra, he grants Hanuman a wish that his overall body will be as sturdy as Indra's Vajra, and that his Vajra might also not hurt him. In conjunction with Indra other gods have also granted him wishes: the God Agni granted Hanuman https://www.reddit.com/user/SwimKey4360/comments/1c5pajo/a_pinnacle_of_hindu_worship_in_adelaide/