As I understand the law, this man should have put the loan terms in writing, filed IRS Form 8300, and carried the IRS Form and loan documents with him. The smartest thing to do is to wire yourself the money in addition to the documentation so that you are not traveling very far with the actual cash. I'll be surprised if he gets it back without getting charged.

IRS Form 8300 info...

https://www.irs.gov/businesses/small...-of-over-10000

Text copied from...

https://cdllife.com/2021/trucking-co...t-authorities/