As The error was done because of the god Indra, he grants Hanuman a want that his physique will be as sturdy as Indra's Vajra, and that his Vajra may also not hurt him. In conjunction with Indra other gods have also granted him wishes: the God Agni granted Hanuman https://www.tumblr.com/hindutempleadelaide/778316437829877760/hindu-temple-in-adelaide-a-sacred-place-for?source=share