Mishnah 11 - Chapter 1 - Pirkei Avot

Avtalyon omer. Chachamim, hizzaharu bedivreichem, shemma tachovu chovat galut vetiglu limkom mayim hara'im, veyishtu hattalmidim habba'im achareichem veyamutu, venimtza shem shamayim mitchallel.

Abtalion used to say: Sages be careful with your words, lest you incur the penalty of exile, and be carried off to a place of evil waters, and the disciples who follow you drink and die, and thus the name of heaven becomes profaned.

Avtalyon says: Sages, take heed of your words [that leave an opening for heretics to stray through them], lest you incur the punishment of exile and you be exiled to a place of "evil waters" and the disciples that come after you drink them and die and the Name of Heaven be profaned. [That is, even though in the place in which you find yourselves there are no heretics, it is to be feared that you may incur the punishment of exile because of a sin of yours and you be exiled to a place where there are people who interpret the Torah at variance with the halachah (this being the "place of evil waters") and they will understand from your words improper things, and the disciples who come after you will "drink" from those things and die in their sin and the Name of Heaven will be profaned. For those vain ideas will remain in the world. As happened in the instance of Antignos Ish Socho and his disciples, Tzaddok and Baythus, whom he told (viz. 1:3): "Do not be like servants who serve their master in order to receive pras" and who said: "Is it conceivable for a worker to labor and exert himself a whole day and not receive a wage at night!" They subsequently succumbed to heresy (and their disciples are called "Tzdokkim" and "Baythusim" to this day.)]