Bava Metzia 81 - What Type of Guardian Are You?

All craftsmen are considered paid guardians. Therefore, they are liable for loss or damage due to their negligence, or even not due to their negligence, provided that it was not unavoidable, such as theft.
Once the craftsman says to the one who hired him, "Take your property and bring the money that is due to me," he is considered unpaid guardian, liable only for loss or damage due to negligence.
One who lends money to another against a security is considered a paid guardian in regard to the security. The lender is permitted to rent the poor man’s security to others in order to reduce the debt, because he is as one returning lost property to its owner.