Bava Metzia 41 - Custodian Breaks the Keg
If one deposited a keg with another for safekeeping, and the custodian moved the keg and it broke through an unavoidable accident, the law is determined as follows:
If the custodian moved the keg for its benefit, such as removing it from an unsafe place - he is not liable to pay compensation, because he remains a custodian.
If however the custodian moved the keg for his own benefit, then at this time he is stealing it, and if it breaks while in his hands, he is liable. If he put it down, then he returned the stolen item and again became a custodian, so he is not liable.