וָאֶקַּ֖ח אֶת־סֵ֣פֶר הַמִּקְנָ֑ה אֶת־הֶֽחָת֛וּם הַמִּצְוָ֥ה וְהַחֻקִּ֖ים וְאֶת־הַגָּלֽוּי׃
So I took the deed of the purchase, both that which was sealed, containing the terms and conditions, and that which was open;
Rashi on Jeremiah
that which was signed, etc. With its signature as it was signed according so the law and the statute.
Rashi on Jeremiah
and that which was open Which was confirmed in the court by word of its witnesses, and the judges wrote and signed a judicial confirmation. This is the confirmation of the deeds to make the matter open and publicized lest the witnesses die, and our Rabbis explained this concerning a plain, open document and a folded one in Baba Bathra (160b).