TALMUD 3

R. Joshua b. Levi said: What is the meaning of the Scriptural verse: And this is the law which Moses set [before the children of Israel]? - If he is meritorious it becomes for him a medicine of life, if not, a deadly poison. That is what Raba [meant when he] said: If he uses it the right way it is a medicine of life unto him; he who does not use it the right way, it is a deadly poison.

-Yoma 72b