vouch

To call on (someone) to be a witness to something.

Nor need I ſpeak my Deeds, for thoſe you ſee, The Sun and Day are Witneſſes for me. Let him who fights unſeen, relate his own, And vouch the ſilent Stars, and conſcious Moon.

To cite or rely on (an authority, a written work, etc.) in support of one's actions or opinions.

But the most catholike and renoumed doctours of Christes religion in the corroboration of their argumentes and sentences, do alledge the same histories and vouche (as I mought say) to their ayde the autoritie of the writars.

[F]or more credit to vvhich aſſertion hee vouched ſundry books, and acts, […]

To affirm or warrant the correctness or truth of (something); also, to affirm or warrant (the truth of an assertion or statement).

Nay tis moſt credible, we heere receiue it, A certaintie vouch'd from our Coſin Auſtria, […]

Deliuer them this Paper: hauing read it, Bid them repayre to th' Market place, where I Euen in theirs, and in the Commons eares Will vouch the truth of it.

To bear witness or testify to the nature or qualities (of someone or something).

If a Man ſucceeds in any Attempt, though undertook with never ſo much Folly and Raſhneſs, his Succeſs ſhall vouch him a Politician; and good Luck ſhall paſs for deep Contrivance: […]

To back, confirm, or support (someone or something) with credible evidence or proof.

[M]ee damp horror chil'd At ſuch bold words voucht with a deed ſo bold: […]

An assertion, a declaration; also, a formal attestation or warrant of the correctness or truth of something.

VVho will beleeue thee Iſabell? My vnſoild name, th' auſteereneſſe of my life, My vouch againſt you, and my place i'th State, VVill ſo your accuſation ouer-vveigh, That you ſhall ſtifle in your ovvne report, And ſmell of calumnie.