Parashat Mishpatim: Dispute over amount of money repaid

"When you Lend Money" (Shemot 22:24)
Dispute over amount of money repaid

Question: I lent someone 400 shekels, and he brought me the money. I counted the money later and only counted 300 shekels. He insists that he gave me 400. What do I do?
Answer: We have a principle "One who wants to extract money from his fellow is obligated to bring proof." The person who to whom the money is due must prove that the other person owes him. If not, he loses out. You needed to create a way to count the money so that it would have been clear how much there was. Our Rabbis say that when you lend money, you should write a document specifying the details of repayment. By having this document, and referring to it when you received payment, you would have been saved from this current dispute. At this point, it is difficult to prove that you are owed anything.