guard one's tongue

guard one's tongue (third-person singular simple present guards one's tongue, present participle guarding one's tongue, simple past and past participle guarded one's tongue)

1. To be careful in what one says; to avoid divulging information or speaking in a way considered to be inappropriate or offensive.
   • 1696, Aphra Behn, “Love-Letters to a Gentleman,” Letter 3, in All the Histories and Novels Written by the Late Ingenious Mrs. Behn, London: Samuel Briscoe, p. 47,

     […] though I scorn to guard my Tongue, as hoping ’twill never offend willingly; yet I can, with much adoe, hold it, when I have a great mind to say a thousand things I know will be taken in an ill sence.

   • 1793, John Trusler, chapter 36, in Life; or, The Adventures of William Ramble, Esq.‎, volume 3, London: for the author, page 86:

     […] of course it is a little out of character to call upon me to guard my tongue, when it is the privilege of a freeman to speak his mind […]

   • 1892, Mark Twain [pseudonym; Samuel Langhorne Clemens], chapter XXIII, in The American Claimant, New York, N.Y.: Charles L[uther] Webster & Co., →OCLC, page 241:

     Oh, Howard, Howard, the things you have uttered when you were forgetting to guard your tongue, have betrayed you.

   • 1948, Lloyd C. Douglas, chapter 2, in The Big Fisherman‎, Toronto: Thomas Allen, page 30:

     But in spite of the affection she felt for her charming mother-in-law, Arnon had extended no confidences. Her father had warned her to guard her tongue in the presence of these people.