As the mistake was completed with the god Indra, he grants Hanuman a desire that his entire body can be as powerful as Indra's Vajra, Which his Vajra can also not harm him. Along with Indra other gods have also granted him wishes: the God Agni granted Hanuman a wish https://hindu-temples-in-adelaide.mystrikingly.com/blog/hanuman-temple-adelaide-connecting-souls-through-prayer