Both that which was sealed... and that which was open. — We are left to conjecture why there were two documents, and why one was sealed and the other open. Possibly, as in modern transactions, one was simply a duplicate copy of the other, the sealed document being the formal evidence of purchase kept by the buyer, and the other left with the vendor for reference. The more probable explanation, however, is that the unsealed document, which the witnesses did not subscribe or see, contained details which did not concern the witnesses, the price paid (though the mention of the witnesses before the weighing of the money militates against this view), the conditions of resumption by the vendor, possibly some reference to the period of seventy years, at the end of which, and not before, the heirs of Jeremiah might expect to enter on possession.
According to the law and custom. — Better, to wit, the agreement and the conditions. The whole transaction may be compared, as an example of ancient conveyancing, with the transfer of the field and cave of Machpelah in Genesis 23