As the error was performed with the god Indra, he grants Hanuman a want that his physique might be as sturdy as Indra's Vajra, and that his Vajra can also not hurt him. Coupled with Indra other gods have also granted him needs: the God Agni granted Hanuman a wish https://durga45420.theideasblog.com/37596803/hanuman-for-dummies