The expression that makes it clear that a person signing a legal document is signing it as a witness.
The initial words of the concluding clause in deeds: “In witness whereof the said parties have hereunto set their hands,” etc. A translation of the Latin phrase “in cuius rei testimonium.”
TLD Example: The modern trend encouraging lawyers and others to prepare legal documents using plain English has resulted in terms such as “in witness whereof” being dropped from general use.