Kalabhairava, the fearsome aspect of Lord Shiva, is the God who is the protector of Benares. Once Brahma insulted Lord Shiva and his fifth head teasingly laughed at Lord Shiva. From Lord Shiva came out the Kalabhairava (Black Bhairava) who tore off the fifth head of Lord Brahma. On the entreaties of Lord Vishnu, Shiva pardoned Lord Brahma. But the sin of beheading Lord Brahma followed Kalabhairava everywhere. Also the head of Brahma stuck to him. To keep away the sin and punishment which were chasing him, Kalabhairava entered the city of Benares. The sin could not enter the city. Kalabhairava was made as the Kotwal of Benares. Kalabhairava rides on a dog. A pilgrimage to Kasi is not supposed to be complete without visiting the temple of Kalabhairava.
Another story identifies Kalabhairava with Veerabhadra who cut off the head of Daksha the father of Sathi Devi, when he insulted Lord Shiva. Sathi's body was cut into pieces and strewn all over India giving rise to Shakthi Peetas. Outside every Shakthi Peeta is the temple for Bhairava.
In another story, Kalabhairava is the form of Shiva who controls the growth and management of time. Whoever wants to spend, manage or ration their time in a proper manner should pray him.
He is also considered as the guardian of temples of Lord Shiva. After locking the doors of the temple of Lord Shiva, the keys are ceremonially offered to Bhairava.
This ashtakam is recited by the priests of the temple of Kalabhairava in Benares before blessing the devotee with a tap by the cane of Lord Kalabhairava.