Story of Gajmukhaasur

7-Story of Gajmukhaasur
[From Shiv Puraan]

Why Shiv Jee sent a part of him to Lord Vishnu when He incarnated as Raam? Because it was an eternal promise to Vishnu which was to be fulfilled.

There was a Gajamukhaasur named Raakshas who did great penance toward Lord Shiv Jee. Pleased with his penance Shiv Jee appeared before him and asked him to ask for a Var. Gajmukhaasur requested Lord Shiv Jee to live in his belly. Since Shiv Jee had promised to fulfill his wish, he had to live in his belly. Now lots of time passed and Shiv Jee was not seen anywhere.

When Lord Shiv Jee did not return for some time, Goddess Paarvatee Jee sought the help of Lord Vishnu. Lord Vishnu dressed himself as a flutist and took along with him Nandee, the steed of Lord Shiv Jee, and wandered on the streets. Wandering around He came to Gajmukhaasur's palace.

Nandee was made to perform funny dances, in front of Gajamukhaasur to the soulful music provided by Lord Vishnu (this type of bull dancing to the tune of music is still prevalent in South India). Gajamukhaasur was very pleased with the whole performance and expressed his wish to gave a boon to Lord Vishnu, without knowing him that who He was. Lord Vishnu requested him to release Lord Shiv. When Lord Shiv came out of Gajmukhaasur's belly, he died. That is how Lord Vishnu freed Shiv from the clutches of Gajmukhaasur and killed Gajmukhaasur also.

It was then Lord Shiv Jee promised Lord Vishnu that he would serve Lord Vishnu in one of His future forms and will help Vishnu the same way He did for him now. So when Vishnu incarnated as Raam, Shiv sent his one of the 11 forms as Hanumaan to help Him.