Here we'll talk about a case where a barrel of oil was broken during the sale. A man sent his son to purchase oil, and the boy had a coin in his hand. The Mishnah says that somebody sends his young son to a shopkeeper to purchase oil with a pundion, which is a coin worth two issarim (small coins). He also has an empty jug in his hand to collect the oil.
The person here wanted to buy a jug full of oil for one issar, and then receive another issar in change. So the oil cost one issar, and he was expecting an issar of change back. The son arrives at the store, gives the pundion to the shopkeeper, and hands him the jug as well. The shopkeeper takes the jug from the boy and uses it to measure oil for a different customer. He thinks, “I know this is a certain amount in this jug. Let me use it, and I'll pour it over to another customer.” Then he measures out a certain amount of oil for the boy, puts it in that jug, and gives him the filled-up jug of oil. He also hands him the change of one issar.
On the way home, the young boy falls and breaks the jug of oil. He also loses the coin. So who is obligated in this case? The shopkeeper is liable to pay for the oil, the issar, and the jug as well. He has to pay for the oil and the issar because he shouldn't have sent them back with the child. The implied understanding between the father and the shopkeeper should have been: “I'm sending my son to you with this money to purchase the jug of oil. I don't want you to give him back the jug of oil. I want you to have it delivered, along with the issar of change, by a responsible adult.” Therefore, the oil and the issar are the shopkeeper's responsibility. The jug is his responsibility as well. Even though the jug shouldn't be his responsibility because the father sent it with the young boy, it becomes his responsibility because he used it negligently, for his own purposes. He wasn't allowed to do that, so he has now taken responsibility for it. He would be obligated until it gets back to the father. Therefore, when it broke here, it was his responsibility.
Rabbi Yehuda argues here. Rabbi Yehuda poter: The shopkeeper is exempt from the liability. He does not have to pay in this situation for the oil, the jug, or the lost coin. According to Rabbi Yehuda, the buyer sent his son with the intention of picking up the merchandise and bringing it back home. The fact that he sends money and the jug in the hand of a child shows that he's okay with his son transporting the goods back home and taking the change back to him. Therefore, the shopkeeper would not be responsible in this situation.
Rabbi Yehuda would agree that the shopkeeper did misuse the man's barrel or jug. He's not allowed to use it for his own purposes to measure out oil for other customers. But that does not make him responsible for what happened later on. So we see a machloket (dispute) between him and the Tanna Kamma (first tanna) over who is responsible. But the Tanna Kamma does agree with Rabbi Yehuda in a certain case. There's no machloket in a certain case, and that's what we're quoting the Hachamim (the Sages) over here. That's the Tanna Kamma. We're quoting Hachamim to Rabbi Yehuda. The Hachamim, the Tanna Kamma, agree with the opinion of Rabbi Yehuda.
If the jug was in the child's hands when he arrived at the store, and the shopkeeper measured the oil out for him into the jug right away, without using it for anyone else, then the shopkeeper would be exempt from liability for the jug if it broke later on, because he did not borrow the jug without permission. He would still be responsible for the oil and the coin because he shouldn't have sent them back with the young child. But regarding the jug itself, Rabbi Yehuda and the Hachamim agree, as long as the shopkeeper wasn't negligent and misusing property that wasn't his.