As the mistake was performed by the god Indra, he grants Hanuman a desire that his overall body will be as powerful as Indra's Vajra, Which his Vajra also can not harm him. Coupled with Indra other gods have also granted him needs: the God Agni granted Hanuman a wish https://hindutempleadelaide.travel.blog/2024/09/29/hanuman-mandir-south-australia-a-premier-hindu-temple-in-adelaide/