As the error was carried out by the god Indra, he grants Hanuman a would like that his human body could be as sturdy as Indra's Vajra, and that his Vajra can also not hurt him. In conjunction with Indra other gods have also granted him needs: the God Agni https://medium.com/@jameag789/exploring-sacred-spaces-in-adelaide-hanuman-temple-shani-dev-temple-c0ef7bfb74d6