Buddha passes through the village of Kesaputta and is greeted by its inhabitants, a clan called the Kalamas. They ask for his advice: they say that many wandering holy men and ascetics pass through, expounding their teachings and criticizing the teachings of others. So whose teachings should they follow? He delivers in response a sermon that serves as an entry point to the Dhamma.
Do not go upon what has been acquired by repeated hearing; nor upon tradition; nor upon rumor; nor upon what is in a scripture; nor upon surmise; nor upon an axiom; nor upon specious reasoning; nor upon a bias towards a notion that has been pondered over; nor upon another’s seeming ability; nor upon the consideration, ‘The monk is our teacher.’ Kalamas, when you yourselves know: ‘These things are good; these things are not blamable; these things are praised by the wise; undertaken and observed, these things lead to benefit and happiness,’ enter on and abide in them.
-Buddha, Anguttara Nikaya Vol 1, 188-193 P.T.S. Ed