As the mistake was completed because of the god Indra, he grants Hanuman a would like that his physique can be as strong as Indra's Vajra, and that his Vajra also can not harm him. Together with Indra other gods have also granted him wishes: the God Agni granted Hanuman https://sites.google.com/view/hanuman-temple-adelaide/hanuman-mandir-and-shani-dev-temple