According to Kantha Puraanam, the six days that Lord Muruhan fought against the demon, Soorapanman, are collectively observed as the Kantha Sashti fast.
Soora Samhaaram: Soorapanman had two brothers, Singgamuhaasuran and Thaarahaasuran and more than two hundred thousand siblings. He had one sister by the name of Ajamuki. Soorapanman and his two brothers performed austere penance and courageous sacrifices to Lord Siva and received from Him the boon that they shall rule the 1008 worlds for 108 yugas, and that they cannot be destroyed by anything or anybody, except for the power of Lord Siva Himself. Soorapanman became arrogant due to this great boon and started to torture the Devas and others.
The Devas beseeched Lord Siva’s help. Desiring to respond to their prayers, Lord Siva, who was in a state of solitude and ecstasy, married Devi Paarvathi and brought forth six flames from His six eyes of wisdom. Lord Siva, who is depicted with five faces, exposed His sixth at that point of time. Lord Muruhan appeared from these flames.
Before preparing for the war, Lord Muruhan sent a peace mission to Soorapanman, but it failed. Hence, Lord Muruhan waged war against Soorapanman. Vaayubahavaan was Muruhan’s charioteer.Thaaraahaasuran was killed by Muruhan’s Vel while Singgamuhaasuran died by Muruhan’s Kulisaayudham. Thaarahaasuran returned to Swami Aiyappan as an elephant to be His vehicle while Singgamuhaasuran went back to Devi Kaali as Her lion. Soorapanman used all his might and magical powers to fight against Lord Muruhan. As all his efforts failed, he stood as a mango tree. The tree was split into two by Muruhan’s Vel. When the two parts of the tree transformed into a rooster and a peacock and went to attack the Lord, they lost their arrogance due to the graceful glance of the Lord, and became His flag’s emblem and vehicle, respectively. The Devas got back their heavenly world and lived happily.