Vouchsafe is a formal and old-fashioned word meaning "to give (something) to someone as a promise or a privilege."

// He vouchsafed the secret to only a few of his closest allies.

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"[Arthur] Conan Doyle (1859-1930) wrote several horribly chilling tales of the supernatural, although this might surprise readers who only know his Sherlock Holmes stories. When there are eerie goings-on in the Holmes yarns, a rational explanation is inevitably vouchsafed, à la Scooby-Doo." — Jake Kerridge, The Daily Telegraph (London), 20 Dec. 2023

Shakespeare fans are well acquainted with vouchsafe, which in its Middle English form vouchen sauf meant "to grant, consent, or deign." The word, which was borrowed with its present meaning from Anglo-French in the 14th century, pops up fairly frequently in the Bard's work—60 times, to be exact. "Vouchsafe me yet your picture for my love," beseeches Proteus of Silvia in The Two Gentlemen of Verona. "Vouchsafe me raiment, bed, and food," King Lear begs his daughter Regan. But you needn't turn to Shakespeare to find vouchsafe; today's writers still find it to be a perfectly useful word.