From the Buddha's Kalama Sutra:

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."
Rather, 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.'