אות - רלו

He said: One must be very careful not to let out from one's mouth any word of wickedness, Heaven forbid — even in a way of mockery. That is — one should not say, Heaven forbid, about oneself that one will be wicked, Heaven forbid, or that one will commit a transgression, Heaven forbid — even if one says this in jest and has absolutely no intention of doing it. Even so, this speech harms one greatly and can compel one, Heaven forbid, afterward to do what one uttered from one's mouth — even though one did not say it sincerely but only in jest. And through this King Yehu stumbled — through uttering from his mouth (II Kings 10:18): "Yehu will serve him greatly." Even though in his heart he intended not to serve him but said this in jest in order to deceive the worshippers of the Baal as is explained there in the Scripture — even so he stumbled afterward through this until he himself worshipped idolatry as our Sages o.b.m. said. Therefore one must be very careful about this — for "a covenant has been made with the lips," etc., as our Sages o.b.m. said (Sanhedrin 102a; Moed Katan 18a).