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When the monks had assembled, Guji ascended the high rostrum, and after a few moments, he began to speak." Today a strange nun appeared and asked me for my true speech. I could not say anything. I don't understand my own true speech-- how c

an I possibly teach Buddha's speech to all of you? That has hit my mind. I have been a monk for thirty years now. I understand all about Buddhism. I understand all the sutras. But still that cannot help me. So today this nun strongly taught me my correct direction. I must answer her question now, before ever opening my mouth again."
This Zen story has hinted to us not to teach buddhism unless you are able to deliver your own true speech.
( In order that you wish to teach your friends Buddhism or spiritual teachings, make sure that you can use your simple and direct language and experience of your own to guide them. And please don't quote and unquote terms and terminology which you yourselves have not fully comprehend the meaning of it and starting teaching your friends. You may be misguiding them. - 2 cents opinion)