Words are not sparrows; once they have flown they cannot be recaptured

The title of my question is a Russian proverb, for which I cannot think of an analog. All the examples I have seen on this website refer to actions rather than specifically speech. Can anyone give me an example of a colloquial phrase about the irreversibility of speech?

Probably not an established set phrase, but I often hear and read:

Words once spoken ( cannot be retrieved, cannot be taken back)

It may derive from the Latin proverb:

Nescit vox missa reverti.

Translation: "A word once spoken can never be recalled." From Horace. Another interpretation: "Think twice before you speak."

The bell, once rung, cannot be unrung.

or

You cannot unring the bell.

Google books traces "cannot be unrung" to 1924:

... what is learned or suspected outside of court may have some influence on the judicial decision. It may be only a subtle or even subconscious influence, but a bell cannot be unrung. Adverse claimants have at least some reason to fear ...

By 1948 it is in the Utah bar bulletin:

if the matter has already been printed and in the hands of the jury, the bell cannot be unrung

by 1956, it was being used as a commonplace in Sandez v US:

Could the court "unring the bell" by subsequently instructing the jury that Exhibit 29 was admissible only against Perno? We think it doubtful.

I also concur with "Let the cat out of the bag". This paints a different word-picture but the sense is similar.