Four-headed Brahma performs the job of creation as per Hindu beliefs. But many scriptures state that Brahma had five heads. He lost his fifth head. As per the story in the Mahabharata, it was Shiva who cut off the fifth head.
Legend has it that Vishnu and Brahma wanted to know who was superior and this led to a fight. Lord Shiva intervened and said whoever can find out the origin or end of Shivling is superior. Lord Shiva appeared before them in the form of a huge pillar of fire. Lord Vishnu went down searching and Brahma went up searching. Both travelled and travelled but never reached the beginning or end.
After the futile search, Lord Vishnu returned and accepted defeat. However, Brahma returned stating that he had found the top portion of the Shivling.
But this was a lie.
For lying, Shiva cut off the fifth head of Brahma.
It must be noted here that there is another famous story associated with Brahma losing his fifth head. You can read that story here.
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