The word “Nandi” was derived from the ancient Tamil word “Pandi” which meant bull. He which serves as the mount of the god Shiva and as the gate keeper of Shiva and Parvathi. He is the chief guru of eighteen masters(18 siddhas) including Patanjali and Thirumular. In one story, it is stated that once Siva and Parvathi were playing a game of dice. They agreed to have Nandi as the umpire. Nandi is a favorite of Siva, although Siva lost the game, he declared him the winner. It is stated that Parvathi was anger over Nandi’s partiality for Siva and cursed him that he should die from an incurable disease. After that Nandi fell at the feet of Parvathi and pleaded for forgiveness. He worshipped Ganapathi by offering green grass. Nandi was then relieved of his dreaded disease. His health improved and by the grace of Parvathi he was compensate for the faults . Nandi who cursed Ravana (the demon King of Lanka) that his kingdom would be burnt by a monkey (Vanara). And later Hanuman burnt Lanka when he went in search of Sita, who was kept prisoner by Ravana in Ashok Vatika.
Lord Siva followed by Nandi came forward to help as he was the only one who could counteract this deadly poison. Siva took the poison into his hand and drank it, the descent of the poison was in turn stopped at His throat, by His divine consort. Nandi saw some of the poison spill out of Siva’s mouth and immediately drank if off the ground. The devas and asuras watching were shocked and thought what would happen to Nandi. Lord Siva calmed their fears saying, “Nandi has surrendered into me so completely that he has all my powers and my protection”.