Once upon a time, Lord Vishnu fought a fierce battle for 10,000 years. After this war, he got tired and came to his Vaikuntha slept with his bow as support. At the same time the plan to perform the yajna by the gods was going on and they came to Vaikuntha along with Brahma and Shiva to meet Lord Vishnu. There, they saw that Lord Vishnu was in deep sleep. Thinking that the sleeping person should not be disturbed, those people stood there. But even after a long time, Lord Vishnu did not wake up from sleep, then after thinking they decided to awaken Lord Vishnu . Then Brahma created a worm and asked it to awaken Lord Vishnu. The worm cut the string of the bow, thinking that this work will give it the remainants from tha yjana in future as said by brahma. A terrible sound was produced after cutting the string of the bow and darkness enveloped all around.
When after some time the darkness gradually subsided, the gods saw that Lord Vishnu’s head was not on his body. Then the gods became very worried, seeing the gods in worry, Brahma Ji said, Gods don’t worry, whatever happens in the world, some reason is there behind it, there is no action without reason. We will worship Goddess Parashakti, surely she will solve this problem. Having said this, Brahma Ji ordered the Vedas to praise the goddess. When the Vedas praised the goddess, the goddess was very pleased.
After this, goddess spoke through her voice she said , dear deities I am very happy with the praise of the Vedas. You do not need to worry. There are two reasons why Lord Vishnu’s head is cut, first of all, once Lakshmi ji had told him to become headless, because Vishnu ji was laughing after seeing Lakshmi ji. The second reason is to end the monster named Hayagriva. There is a monster named Hayagriva. He did penance for 1000 years after renouncing food and water. At that time this monster had subdued all his senses and used to chant only one of my single lettered mantra. He did such austere penance to get a glimpse of my Tamasi form, then I Parashakti revealed in front of this monster in my Tamasi form.
Seeing the Goddess appear in front of him, this monster was very pleased and stood up. He began to revolve around that form of mine and praised me. I asked him to ask for the desired boon. Then she said Goddess I want to be immortal. Hearing his words, my Tamasi energy said , demon hayagreeva t death is for everyone in the world , this is the rule. I will not break this rule, that is why you should consider asking for another boon. After that the monster asked hoon from me that, he should die only by the hands of Lord Hayagreeva. Then I gave him the boon of getting death from the hands of hayagreeva.
At this moment, the same monster is missing his powers and causing suffering Brahmins, Gods and sages. In order to free everyone from the tyranny of this monster, it is necessary to have the head of Lord Vishnu replaced with the head of horse. That is why his head is cut today. Lord Brahma, you cut off the head of a horse and put it on Vishnu’s body, this will lead to his hayagriva incarnation and he will end that hayagriva monster. Saying this, the goddess disappeared. After this, Brahma Ji cut off the horse’s head with his sword and placed it on Lord Vishnu’s body and at that moment Lord Vishnu woke up and stood in front of gods. In this way there was a Hayagriva incarnation of Lord Vishnu.
After this, terrible war broke out between horse headed incarnation Hayagriva of Lord Vishnu and that monster named Hayagriva. It was not so easy to kill him, Lord Vishnu fought with him for a long time, later according to the boon of Goddess Jagadamba, by the hands of Lord Hayagreeva ,life of demon hayagreeva came to an end.