Where does the Buddha compare the Dharma to leaves on a tree?

There is a story in the Pali Canon where the Buddha compares the Dharma to leaves on a tree. If I can give a very approximate quote to what I remember > The dharma that I have taught is just a handful of leaves. The Dharma > is actually all the leaves in all the trees So the point been that there is a lot more to the Dharma then what the Buddha is teaching at that point. Can anyone give the exact reference for that story - I'm fairly certain it is from the Pali Canon.