Brahma's Fifth Head - Brahma Purana Part-22

Years ago, there was a war between the gods and the demons and the gods lost. The gods came to Brahma for advice and Brahma asked them to pray to Shiva.

When Shiva appeared before them, the gods said, "The demons have defeated us. Please kill them and save us."

Shiva went to fight with the demons. He drove the demons off from Mount Sumeru and out of heaven. He pursued them to the ends of the earth. All this exertion made Shiva sweat. And wherever the drops of sweat fell down on the ground, terrible ogresses named matris were created. The matris also started to kill the demons and pursued them down to the underworld.

While the matris were killing the demons in the underworld, Brahma and the other dos waited on the banks of the river Goutami Ganga. This place came to be known as Pratishthana.

When the matris had killed all the demons, they returned to earth and began to live on the banks of the Goutami Ganga. This tirtha has come to be known as matritirtha.

Brahma used to have five heads. The fifth head was in the shape of a donkey's head. When the demons were running away to the underworld, this donkey's head addressed the demons and said, "why are you running away? Come back and fight with the gods. I shall aid you in your fight."

The gods were alarmed at this paradoxical situation. Brahma was helping them in their flight with the demons and Brahma's fifth head was trying to help the demons. They went to Vishnu and said, "Please cut off Brahma's fifth head. It is causing too much of confusion."

"I can do what you want," replied Vishnu, "but there is a problem. When the cut-off head falls on earth, it will destroy the earth. I think you should pray to Shiva to find a way out."

The gods prayed to Shiva and Shiva agreed to cut off the head. But what was to be done with the severed head? The earth refused to bear it and so did the ocean. Finally it was decided that Shiva himself would bear the head.

The place where Shiva cut off Brahma's fifth head is known as rudratirtha. 

Ever since that day, Brahma has had four heads and is known as Chaturmukha (chatur connotes four and mukha connotes face). There is a temple to Brahma on the banks of the Goutami Ganga. This is a holy place known as brahmatirtha. A killer of brahmanas is pardoned his sin if he visits this temple.