We learn in yesterday’s Parsha the strength of the שבועה, oath, in order to settle disputes.
There is a concept called שבועה דאורייתא, or Torah oath in three situations. The first case is where there is only one witness to prove a claim. If supplemented with this שבועה, claim is accepted. The second situation is where there is a שומר, watchman, who claims that the object under his care was stolen. He must swear that he had nothing to do with the theft. And the third case is מודה במקצת, where one admits part of a loan obligation but not all of it. He must swear that he actually owes only that particular amount.
This Torah oath was made in בית דין by holding on to a Torah scroll and swearing in Hashem’s holy name. This was meant to impress upon the individual that he must tell the truth.