The power of life and death is in the tongue.
“Despite Enoch’s positive example, humanity continued in its downward spiral of moral degeneration. Eventually, G‑d saw that the only remedy was to give humanity a fresh start.
G‑d saw how great was humanity’s wickedness. Genesis 6:5
When G‑d saw humanity’s moral state, He did not at first express His decision to wipe out the world with a flood. Only after He formulated a way for humanity to survive (i.e., through Noah) did He pronounce His decision. This was because once an idea descends from thought into speech, its reality becomes more concrete and therefore it becomes harder to revoke.
Similarly, we should always be aware of the awesome power of speech: By articulating a negative assessment of someone – even if they are unaware that we have done so! – we have unwittingly reinforced their negative traits and made it harder for them to rid themselves of them.
We should therefore think twice before uttering a negative judgment about anyone; on the contrary, we should always seek to make positive, constructive comments about others. Doing so reinforces their positive traits and raises them to greater spiritual heights.1Likutei Sichot, vol. 15, p. 29 ff.