תנ״ך אויף קהלת 5:6

For a dream comes with much preoccupation [(with a particular thought in the daytime)], and the voice of a fool with a multitude of words [(wherefore I say: "Let your words be few.")]

Do not allow your mouth to bring sin upon your flesh [i.e., upon your children.] And do not say before the messenger [(who comes to claim the charity that you pledged in public)] that it [(your vowing)] was a mistake. Why should G-d be angry at [i.e., because of] your voice, and destroy the work of your hands [(the mitzvoth that you have already done)]?