פירוש על בבא קמא 6:5

One who lights a stack of grain and there were vessels and they burned etc...

המדליק את הגדיש – he kindled it within his own [property] and it went and consumed that of his fellow.

If a man set fire to a stack and in it there were utensils and these caught fire: Rabbi Judah says: “He must make restitution for what was therein.” But the Sages say: “He need only pay for a stack of wheat or barley.”
If a kid was fastened to it [to the stack] and a slave stood near by, and they were burnt with it, he is liable. If there was a slave fastened to it [to the stack] and a kid stood near by and they were burnt with it, he is not liable.
The Sages agree with Rabbi Judah that if a man set fire to a large building, he must make restitution for everything therein; for such is the custom among men to leave [their goods] in their houses.
The final two mishnayoth of chapter six continue to deal with damages caused by fire. We learned in the previous mishnah that a person who sets a fire is liable not just for the destruction of crops but also for the damage done to the field itself. Mishnah five deals with damages done to various things that may be on a field. Mishnah six deals with fires that may have been set accidentally.
Section one of mishnah five contains a dispute between Rabbi Judah and the sages with regards to fire damage done to utensils that were placed inside a stack of wheat. According to Rabbi Judah one is liable for the damage done to the utensils as well as the wheat (or barley) itself. According to the Sages the kindler’s liability is limited to the wheat. For the damage done to the utensils he is exempt. Section three can help us understand the basis for this dispute. There we learn that the Sages agree with Rabbi Judah that if one burns a building he is obligated also for the things left inside, because it is customary for people to leave things in buildings. In comparison, we can see that the Sages think it is not customary for people to leave things in stacks of hay. Therefore a person who burns a stack of hay is exempt if someone left in there an item that is not usually left in a stack of hay. Rabbi Judah probably assumes that it does not make a difference if people normally leave things in the place that was burnt. Since the person caused the damage he is liable in any case.
Section two deals with a case where a kid (small goat) and/or slave were found near or tied to the stack of hay and were burnt and killed in the fire. We will discuss the second clause first. Here the slave is tied to the stack of hay when he was burnt and killed. When the mishnah says that the person is not liable, the meaning is that he is not liable for monetary remuneration. The reason is that he will receive a more severe penalty for killing the slave. In Jewish law there is a principle that one cannot receive two punishments for one crime. In this case the person killed another person and caused damage to property at the same time. For killing, the person is obligated for the death penalty and therefore he cannot also receive a monetary fine. (For a different example see Bava Kamma 3:10). In the first clause the slave was only near the stack but not tied to it. Since the slave could have run away the kindler is not liable for the death penalty and therefore he will be liable for damages.

That he lights in his own domain and it went, and it consumed in the domain of his friend; in this example the sages say he only pays for the tack but not the vessels. However we evaluate the place (displacement) of those vessels as if they were full of grain. But if he kindled a stack of his friend he pays for vessels that are inside of it. And only vessels that are normal to place in the stack, for example a plow or a winnower[look up]. But aside from these types of vessels he is not obligated except for the amount of the body from the grain as we mentioned. And if he lit the tower, the owner of the house swears on what was inside of it a Torah oath and the one who lights it will pay all the owner of the house swears on it. And only the evaluation that there is to him the amount he says he lost inside the fire. And the halakah is not like Rav Yehudah.

ר' יהודה אומר ישלם כל מה שבתוכו – that Rabbi Yehuda obligates on hidden damage in the fire, for he does not have (i.e., hold) the expounded teaching on "או הקמה"/or the standing grain (see Exodus 22:5). Just as the standing grain is uncovered, even all that is uncovered.

וחכ"א אינו משלם אלא גדיש וכו' - they have (i.e., “hold by” this expounded teaching of "או הקמה" and exempt on all damages that are hidden in the fire, but they estimate the place of the utensils as if it is a heap of grain. And he pays the heap of grain like the measure of the body of the utensils and when we stated the end [of our Mishnah]: “And the Sages agree with Rabbi Yehuda” – when he sets fire to a large building, that he pays for all that is inside it. And it is proven in the Gemara (Tractate Bava Kamma 61b) that Rabbi Yehuda and the Rabbis disagreed also with one who kindles a fire in [the property] of his fellow, as Rabbi Yehuda holds that if he lights a fire in that of his fellow, he pays for everything that is within it, and even for a money-bag (or a purse hanging from the neck). But the Rabbis hold that utensils that one ordinarily hides in a heap of sheaves such as threshing sledges (i.e., an implement with grooves and indentations) and the utensils of cattle he pays for; utensils that one customarily does not hid in a heap of sheaves, he does not pay. And the Halakha is according to the Sages.

היה גדי כפות לו חייב – for living creatures are also included in "או הקמה"/or standing grain. And because of the case that he who has committed two offenses simultaneously, must be held answerable for the severer only, he cannot be exempted. That he is not liable for death on the slave, for since he was not tied up, he could have fled and would exempt about him from the death penalty and from payments. But if he was a slave tied up, he would be exempt even on the kid and on the heap of sheaves, but he would liable for the death penalty on the slave – for he who has committed two offenses simultaneously, must be held answerable for the severer only. But concerning the kid, it makes ono difference whether it was tied up or not tied up, for since it (i.e. the Mishnah) took the language of the slave, it took the language of the kid as well.

במדליק את הבירה – when he kindles within that of his fellow and it is as if he destroys with his hands, and even so, the reason because it is the manner of people to leave their utensils in their houses, but a heap of sheaves, where it is not the manner of people to leave it other than like a threshing sledge (i.e., an implement with grooves or indentations) or the instruments for cattle. Even though I will kindle with that of my fellow, he doesn’t pay, according to the Sages other than things that it is customary to hide in a heap of sheaves.