Nandi is the guardian of Lord Shiva and had sheer devotion towards Shiva. Once, some evil men barged into Shiva’s place. Shiva wanted Nandi to be on his side to fight against the bad men. But Nandi did not listen to Shiva’s words. He ran behind those men despite Shiva denying so. This made Shiva very angry and told Nandi to stay outside of Shiva’s residence. This is why we see Nandi outside of Lord Shiva’s Chamber in temples.
MORAL: Think well before you act and always obey your master’s words.
