Judaism may be a religion of action (mitzvot), but speech — words — are, perhaps, considered equally powerful. In the creation story of Genesis I, God speaks the world into being. (“And God said: ‘Let there be light.’ And there was light.”)
In addition, the perils of lashon ha-ra (evil speech) are well documented in Jewish sources.
The rabbis [of classical Judaism in late antiquity], in inveighing against it, often resorted to hyperbolic language, e.g. in saying that slander, talebearing, and evil talk were worse than the three cardinal sins of murder, immorality, and idolatry. Of one who indulges in leshon ha-ra they say that he denies the existence of God, and that the Almighty declares â€œI and he cannot live in the same worldâ€? (Babylonian Talmud Arakhin 15b). (MORE)
The first chapter of Pirkei Avot has several admonitions relating to speech, including two toward the very end of the chapter.
15. Shammai said: Make your study of the Torah a fixed habit. Say little and do much, and receive all men with a cheerful face.
17. Shimon his [Rabban Gamaliel's] son said: All my days have I grown up among the wise and I have not found anything better for a man than silence. Studying Torah is not the most important thing rather fulfilling it. Whoever multiplies words causes sin.
Earlier in the chapter, Yosi ben Yochanan warned against speaking to women too much and these later, general warnings about speech lessen the misogynistic blow of Yosi’s words a bit.
While Shimon, here, does advocate silence, the overall message does not seem to be the value of complete silence as is found in the monastic traditions of other faiths. Rather, the Rabbis seem to be warning against excessive speech. And, perhaps, in particular, speaking about doing things.
Indeed, speech and action are different domains and to mix the two is to confuse the two. This is, perhaps, why excessive speech could lead to sin. By speaking about what one must do, one can muddle the purpose of it, perhaps even talk oneself out of it.
Better just to do. And to keep one’s mouth shut whenever possible.