As the mistake was completed from the god Indra, he grants Hanuman a would like that his human body can be as solid as Indra's Vajra, Which his Vajra may also not harm him. As well as Indra other gods have also granted him needs: the God Agni granted Hanuman https://www.diigo.com/item/note/b3og4/jq79?k=08eb1c3a062feca0008f53e4794e8cd0