We begin the eighth chapter, Mishnah 1. The next three Mishnayos deal with additional halachos of watchmen - laws of guardianship, responsibility, and liabilities. The first Mishnah before us deals with a law that is perhaps the most difficult to understand in all the laws of damages, known as "be'alav imo" (its owner is with him).
This law opens a window to a fundamental understanding: even though the civil laws - the halachos between man and his fellow - appear to be logical societal rules, they are in fact decrees of the King, decrees of the Almighty. In this case in particular, the law seems technical and even arbitrary, and it does not sit well with our intuition of how it ought to be. It is a unique and difficult law, and this is how it operates.
The Foundation of the Law:
The verse speaks, in the context of the various types of watchmen, about a situation where the owner of the object - referred to here as the cow - lends it to his fellow, and at the time of the borrowing, the owner of the cow is in the service of the borrower. That is to say, at the exact moment the borrower takes possession of the cow, the owner is working for the borrower or serving him in some other way - whether for payment or for free, whether the service is related to the cow or not related to it at all.
If the lender is in the service of the borrower at the time the transfer of guardianship takes place, the borrower is exempt from all responsibility: not only from unavoidable accidents, but even from theft and loss, and even from negligence. And although the verse speaks of a borrower - who has the highest level of liability among watchmen - a kal vachomer derivation dictates that watchmen with lesser responsibility are also exempt.
It turns out that even a paid watchman and an unpaid watchman, if the law of "be'alav imo" applies to them - meaning that at the time they took possession of the object, the one giving it was in their service - they are completely exempt from liability. "In his service" means whether he is employed by him, washing his dishes or plowing his field, or whether he is not employed by him at all but is merely doing him a favor, such as going to bring him a cup of water. It makes no practical difference.
The Source of the Law in the Verse:
The verse in the book of Shemos says that if a person borrows from his fellow, and the borrowed item breaks - such as a broken leg on a cow - "o meis" - or it dies, and "be'alav ein imo" - its owner is not with him, he shall surely pay. And here is where the received tradition comes in: to be "with him" means to be with him in his work at the time the deposited object passes into the domain of the watchman.
The intention is not referring to the situation between them or the location where they were relative to one another at the time of the death or the loss; the matter is determined by the time the transfer of guardianship takes place. And the verse continues: "im be'alav imo lo yeshalem" - if the owner of the borrowed cow is with him, with him in his work, whether for payment or for free, the watchman does not pay for what happens afterward.
The Language of the Mishnah:
This is the law, this is the rule, and this is the central idea of the Mishnah before us. The Mishnah lists three cases of exemption:
"Hasho'el es haparah vesha'al be'aleha imah" - the borrower of the cow borrows its owner along with it, so to speak: I am taking your cow, and at that very moment you agree to be in my service for free - bring me a cup of water.
"O sachar be'aleha imah" - the borrower pays to hire the owner together with the cow: I am taking your cow, and two things are occurring at once - you are lending me the cow, and you also agree to plow my fields with it. In such a case the law applies, since the owner is simultaneously obligated to work for the borrower. And again, this does not depend specifically on working with the cow; even if he agreed to handle tax matters at the same time he took his cow, it is sufficient.
"O sha'al es habe'alim o secharan ve'achar kach sha'al es haparah" - first the borrower took the owner into his service, whether for payment or for free, and only afterward, while the owner is already in his service, he borrowed the cow from him. The events do not occur simultaneously; rather, the work began first, and while the owner is providing his service to the borrower, he borrowed the cow.
"Umeisah - patur" - if the cow died afterward, the borrower is exempt, as it is stated: "Im be'alav imo lo yeshalem". The owner of the borrowed object is with him, with the borrower or with the watchman - whether he is a paid watchman or an unpaid watchman - and he does not pay. And again, the main point is this: "with him" means with him in his work at the time the transfer of guardianship took place.
The case where he is liable:
"Sha'al es haparah v'achar kach sha'al es haba'alim o secharan, umeisah - chayav" - the borrower first took the cow, and only afterward asked the owner to do him a favor, to plow with him or help him, or he hired him for pay for some job - whether to help plow with the cow or to take care of tax matters, it makes no difference.
And even if the owner of the cow is the one pushing the cow at that moment, as long as the agreement to help push it was made only after the borrowing or renting took place - even though physically they are standing together, holding onto each other, and the owner is pushing the cow - it is of no consequence. He is liable. The borrower is responsible to return it, since this is the general rule of a borrower, except for that strange exception of "be'alav imo", which depends solely on the time the transfer of guardianship occurred. A connection formed afterward makes no difference, and the borrower will have to pay.
As it is stated: "Be'alav ein imo shalem yeshalem" - if the owner is not with him, with the watchman, at the time the guardianship is transferred, he shall surely pay. The borrower, or the watchman, will have to pay: the Torah obligates the borrower even for unavoidable accidents, and the paid watchman for theft, loss, and the like.
In summary: In this Mishnah we learned the law of "be'alav imo" - that if at the time of the transfer of guardianship the owner of the object is in the service of the watchman, for pay or for free, in work related to the object or unrelated to it, the watchman is exempt from all responsibility, and even from negligence. The Mishnah listed three cases for exemption, and all of them are when the service preceded the transfer or was done simultaneously with it; whereas when the cow was borrowed first and the owner entered the service of the borrower only afterward - he is liable. Everything depends solely on the time of the transfer of guardianship.