avouch

• Happily I cannot here be judged as a sentimental visionary for my companion will avouch the facts. —  The Adventure of Living
• It was in the same spirit, when, visited by the greatest living statesman of New England, that sterling patriot, and that peerless orator of his whole country, Edward Everett, who, seeing the faculties of Mr. Tazewell still vigorous in his 85th year, expressed to him his regret that he had retired from public life so early, he replied: “I'm only sorry that I ever entered it at all;” when all who knew Mr. Tazewell intimately can avouch that, even at that moment of his 85th year, if the State of Virginia had called upon him to defend her right or honor in any transaction which may have occurred from the settlement of Jamestown to the late Ohio boundary discussion, he would have had every mouldering record from the office of the General Court, and every book bearing upon the subject, clustering in heaps around him in less than sixty hours after he had undertaken his task. —  Discourse of the Life and Character of the Hon Littleton Waller Tazewell
• This Povy had the wit to yield to; and so when it come to be inquired into, I did avouch the truth of the account as to that particular, of my own knowledge, and so it went over as a thing good and just — as, indeed, in the bottom of it, it is; though in strictness, perhaps, it would not so well be understood. —  Diary of Samuel Pepys, November 1668
• {32} and to what incumbrances the House itself had then drawn him, His Majesty was not well used, though I lay not the blame on the whole suffrage of the House, where he had many good friends; for I dare avouch it, had the House been freed of half a dozen popular and discontented persons (such as, with the fellow that burnt the temple of Ephesus, would be talked of, though for doing mischief), I am confident the King had obtained that which, in reason, and at his first occasion, he ought to have received freely, and without condition. —  FRAGMENTA REGALIA
• (This even rebellion must avouch); yet hear —  The Life of Lord Byron

Roget's II: The New Thesaurus

Allen's Synonyms and Antonyms