Drawing on my fine command of language, I said nothing. – Attributed to Robert Benchley by Evan Esar in 1949, however a similar saying alr

Once a word has been allowed to escape, it cannot be recalled. – Horace

And there is monologue disguised as dialogue, in which two or more men, meeting in space, speak each with himself in strangely tortuous and circuitous ways and yet imagine they have escaped the torment of being thrown back on their own resources. – Martin Buber (1878—1965), translated from German