Nandi is usually seen sitting opposite the main door of the temple where Shiva’s murti or Shivalingam is located. He is not waiting for Shiva to come out and say something; he is simply ‘in waiting’.
Nandi is a symbolism of eternal waiting, because waiting is considered the greatest virtue in Indian culture. One who knows how to simply sit and wait is naturally meditative. He is not expecting anything. He will wait forever. Nandi is Shiva’s closest accomplice because he is the essence of receptivity.
Before you go into any temple, you need the quality of Nandi – simply to sit. So just by sitting here, he is telling you: “When you go in, don’t do fanciful things; don’t ask for this or that; just go and sit, like me.” This is the fundamental difference between prayer & Meditation: prayer means you are trying to talk to God. Meditation means you are willing to listen to God. You are willing to just listen to existence, to the ultimate nature of creation.
You have nothing to say, you simply listen.