As all the world should know, the Monkey God Hanuman was completely devoted to his Lord Rama, and his strength and devotion helped Rama greatly when he was battling to rescue his wife Sita from the demon Ravana. For example, it was Hanuman who found her, held captive in the gardens of Ravana, by leaping across the wide ocean to the island of Lanka in the service of his Lord. But one of his greatest feats was when he saved the life of Rama’s brother, Lakshmana.
In the final battle with Ravana and his army of demons, it happened that Lakshmana was mortally wounded. He seemed destined to die, but it was thought that a certain herb growing on a mountain in the Himalayas might perhaps save his life. Hanuman offered to fly there and bring the herb, but when he got to the mountain he found that there were many different herbs growing on its slopes. Fearful that he might bring back the wrong herb, and knowing that time was short, Hanuman made himself as large as a mountain, ripped the entire peak from the earth and flew back to Lanka with it.
Thus, by the help of the correct herb, Lakshmana was saved, and Rama was able to defeat Ravana and rescue Sita.