Yosef Karo, Shulchan Aruch — Choshen Mishpat 43
“ Paragraph 8-When do we say the lender may collect from unencumbered lands? Where the witnesses did not intentionally predate the document. There are those that say that witnesses are believed on this issue, even if we have a copy of their signatures from another source. The same applies to any error that witnesses often make and they are believed to say they erred. There are those that disagree. If, however, the witnesses intentionally predated the document, the lender can certainly not even collect from unencumbered land because the witnesses are invalid witnesses who signed falsely. ”
