Do not believe anything (simply) because you have heard it.
Do not believe in traditions because they have been handed down for many generations.
Do not believe in anything because it is spoken and rumored by many.
Do not believe in anything (simply) because it is in your religious books.
Do not believe in anything merely on the authority of your teachers and elders.
But after observation and analysis, when you find that anything agrees with reason and is conductive to the good of and benefit of one and all then accept it and live up to it.
– Gautama Buddha, Anguttara Nikaya vol I