Do not believe in 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 found written 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 that agrees with reason and is conducive to the good and benefit of one and all then accept it and live up to it.
This is a wonderful truth that is well worth pondering on throughout one’s life. It is very applicable to all areas of our lives, and not just the spiritual. I think the Buddha is almost certainly unique in telling us not to believe what he says simply because he said it, or because some dusty old scripture says so, but to prove it in our own experience. It would be wonderful if more spiritual traditions in the world were as open-hearted as this.