"The Turning of the Wheel of Truth" is certainly the most famous sutta (teaching) in the Pali literature. In his first talk, given to a group of five disciples, the Buddha expounds truths about life and a program for liberation, which he represents as an inner wheel symbolizing the Four Noble Truths and an outer wheel symbolizing the Eightfold Path.
Samyutta Nikaya (Connected Discourses) #56