This Mantra / Mantra of Hanuman Ji is usually chanted frequently at time of worship. To prove this mantra, There's a legislation of chanting 1.25 lakh mantras and twelve in addition to a half thousand sacrifices. Tulsidas has composed this to encourage spiritual aspirants to become devotees of Lord Rama https://lifesdirectory.com/listings13221301/hanuman-mantra-an-overview