Hanuman was 1 of such 4 monkeys. This monkey group was instrumental in offering Rama key information about Sita. They helped him produce a bridge over the seas, and cross above that has a monkey army that efficiently stormed the demon stronghold and freed Sita. Lord Śiva mentioned to him: https://charliesundr.newbigblog.com/44046064/how-much-you-need-to-expect-you-ll-pay-for-a-good-mohini