As the mistake was completed with the god Indra, he grants Hanuman a wish that his body will be as sturdy as Indra's Vajra, and that his Vajra could also not hurt him. Along with Indra other gods have also granted him wishes: the God Agni granted Hanuman a want https://medium.com/@HinduTempleAdelaide/discovering-spiritual-sanctuaries-hanuman-ji-mandir-in-adelaide-d56457ab67e4