Varaha Deva narrated the background of Rudra Vratha to Devi Prithvi. At the time of Creation, Brahma created Rudra and the ‘Pingala Varna’ (red colour) of Rudra became ‘Nilalohit’ (blue colour). Out of fun, Brahma carried Rudra on His shoulders; Rudra found the fifth head of Brahma uttering an ‘Atharva Veda Mantra’ including a word ‘Kapala’which irritated Rudra and He nipped off the Fifth Head of Brahma. As the Kapala of Brahma’s Head got stuck in Rudra’s hands, apparently due to the sin of ‘Brahman Hathya’ (Killing of a Brahmana), Rudra enquired of Brahma as to how to get rid of the skull and the reply was that Rudra should perform Kapala Vrath. Rudra left for Mahendra Mountain and split the skull into three parts; the first part having thick hairs which was converted as Yajnopaveeth of Rudra; holding the second and third parts of the skull on hands, Rudra wore the broken parts and used them as ‘jatajut’ of Himself and the third remainder was taken from ‘Tirthas after Tirthas’ for Body Purification and penance for twelve years among Sapta Dwipas. In the first year He bathed in the Ocean first and in Ganga; in the subsequent years, He bathed in Sarasvathi; in the Sangam of Yamuna, Ganges and Sarasvathi Rivers; there after in the Rivers of Shathadu, Chandrabhaga, Gomati, Sindhu, Thungabhadra, Godavari and Gandaki. Thereafter, Lord Rudra bathed with the skull in hands at Udveg Theerth, Rudramahalaya Theerth, Daruvan, Kedarnath, Bhadreswar Theerth, and Gaya Theerth where Pitru Tarpan was performed. In the sixth year, while performing ‘Vishva Bhraman’ or Universal Circumambulation, Rudra’s Koupeena Vastra along with the ‘Kati Sutra’ ( waist string) fell in a river and since then He had been bathing as ‘Nagna Murthi’ ( or Naked Deva). Thus in the pretext of Kapala Vimochana, Rudra Deva was bathing in nude eversince till the Tirtha Vrata was taken up. At Varanasi, after bathing in Ganges which was indeed the starting point of the Vratha, Kapala Vimochan (relief of the skull) was accomplished and hence the Kasi Theerth was declared as the Kapala Vimochana Theertha; incidentally Rudra Deva’s complexion changed from Neela Varna back to Pingala Varna. The propitious Vratha of Rudra had come to be known as Nagnakapaal Vratha, Vyabhrava Vratha (since the complexion of Rudra got transformed) and Shuddha Shaiva Vratha eversince.