As the mistake was performed through the god Indra, he grants Hanuman a wish that his body might be as robust as Indra's Vajra, Which his Vajra also can not hurt him. In conjunction with Indra other gods have also granted him wishes: the God Agni granted Hanuman a desire https://lukas67qg2.tinyblogging.com/the-best-side-of-hanuman-80824649