With regard to the halakha that one must pay the full cost of the damage in a case where there was no intent to cause damage, the Gemara asks: From where are these matters derived? Ḥizkiyya says, and similarly, the school of Ḥizkiyya taught: The verse states: ''Wound for wound [petza taḥat patza]'' (Exodus 21:25). This phrase is superfluous, as the Torah states elsewhere (see Leviticus 24:19) that one is liable to pay compensation when injuring another. This verse serves to render him liable to pay for the unintentional damage just as he pays for the intentional damage; and he pays for damage caused by accident just as he pays for damage caused willingly.

The Gemara asks: But this verse is necessary in order to indicate that one must pay compensation for pain, even in a case where he pays compensation for damage caused by the injury. Consequently, it seems that that verse cannot also be the source of the principle derived by the school of Ḥizkiyya. The Gemara answers: If it is so that the superfluous phrase is intended to teach only that, then let the verse write: Petza befatza, which carries the same meaning. What, then, is meant by the superfluous word taḥat in the phrase ''petza taḥat patza''? It indicates that we must derive two conclusions from it: That one is liable to pay for pain even in a case where he pays compensation for damage, and that he is liable for unintentional damage as he is for intentional damage, and for damage caused by accident as for damage caused willingly.

§ Rabba says: If there was a stone lying in one’s lap and he was unaware of it, and he arose and it fell and caused damage, with regard to damages he is liable to pay the full cost of the damage caused by the stone. With regard to the four types of indemnity, he is exempt. With regard to Shabbat, if the falling stone caused him to violate one of the prohibited categories of labor; for example, if the stone fell from a private domain to the public domain, he is exempt. The reason is that the Torah prohibited only planned, constructive labor on Shabbat, and he did not plan to perform this labor. With regard to exile, the punishment prescribed for one who unintentionally but negligently kills another, were this stone to kill someone he is exempt, as the incident is deemed accidental.

With regard to a Canaanite slave whose tooth was destroyed or eye was blinded by the stone, potentially enabling the slave to earn his freedom (see Exodus 21:26–27), this is the subject of a dispute between Rabban Shimon ben Gamliel and the Rabbis, as it is taught in a baraita (Tosefta 9:25): If the master was a doctor and the slave said to him: Paint the lid of my eye in order to heal it, and the master blinded it during the procedure, or if the slave requested from his master: Scrape my tooth in order to heal it, and the master knocked out the tooth while scraping it, the slave has mocked the master, as he is emancipated due to the act of the master himself.

By contrast, Rabban Shimon ben Gamliel says: The slave is not emancipated in these cases because the verse states: ''And destroy it'' (Exodus 21:26), from which it is derived that the slave is emancipated only in a case where the master intends to destroy the eye or the tooth, but not if he intended to heal the slave. So too, in the case where a stone fell and accidentally blinded a slave’s eye or knocked out his tooth, according to the Rabbis the slave would be emancipated and according to Rabban Shimon ben Gamliel he would not. All of the above cases relate to situations where the individual did not know the stone was in his lap.

If he was initially aware of it but forgot about it and he arose and it fell, with regard to damages he is certainly liable, being that he is liable even if he was unaware of the stone. With regard to the four types of indemnity, here too he is exempt, as he did not intend to cause injury. With regard to exile he is liable, as the verse states: ''One who unwittingly strikes a person mortally'' (Numbers 35:11), indicating by inference that the assailant had some previous awareness, and in this case he was in fact previously aware of the stone in his lap. The term ''unwittingly'' is employed to describe someone who possessed knowledge of the potential transgression then forgot about it. With regard to Shabbat he is exempt, as this was not a planned, constructive labor. With regard to a slave, the same dispute between Rabban Shimon ben Gamliel and the Rabbis applies.

In a case where he intended to throw the stone, and he intended to throw it for a distance of only two cubits but instead he threw it a distance of four cubits, as it went farther than he wanted it to go, with regard to damages he is liable. With regard to the four types of indemnity he is exempt. With regard to Shabbat he is exempt, as we require planned, constructive labor as a condition for liability. With regard to exile he is liable, as the Merciful One states in the Torah: ''If a man lie not in wait'' (Exodus 21:13), which serves to exclude from the death penalty a situation where one intended to throw the stone for two cubits but he actually threw it for four cubits, as he did not intend to kill, so he is exiled. With regard to a slave, the same dispute between Rabban Shimon ben Gamliel and the Rabbis applies.

And if he intended to throw the stone four cubits but instead he threw it eight cubits, with regard to damages he is liable. With regard to the four types of indemnity he is exempt. With regard to Shabbat, if he said to himself when he threw the stone that he would be satisfied wherever it may land, then yes, he is liable, as he intended to throw it a distance of four cubits, which is the minimum necessary to violate the prohibited labor of carrying in the public domain. If he did not throw the stone aimlessly but rather had selected a target that was four cubits away, then he is not liable as he did not perform the precise planned, constructive labor that he had intended. With regard to exile, the Torah states: ''If a man lie not in wait'' (Exodus 21:13), which serves to exclude from the death penalty a situation where one intended to throw it four cubits but he actually threw it eight cubits, as he did not intend to kill, so he is exiled. With regard to a slave, the same dispute between Rabban Shimon ben Gamliel and the Rabbis applies.

§ Since the Gemara cited Rabba’s comments about various actions for which the perpetrator is liable with regard to certain matters but exempt with regard to others, the Gemara cites similar rulings: And Rabba says: If one threw a vessel, such as an earthenware jug, from a roof and another came along and broke it with a stick during its descent, the latter is exempt from liability. What is the reason? It is because he broke a broken vessel, meaning that once the vessel was thrown from the roof it was clear that it would be broken upon landing, and therefore it is considered as if it were already broken and the one who broke it while it was still in the air is not liable.

And Rabba says: If one threw a vessel from a roof and there were cushions or blankets below so that if the vessel would land on them it would not break, and then another came and removed the cushions or blankets, or if the individual who threw the vessel went quickly before it landed and removed the cushions or blankets himself, and as a result the vessel shattered, the one who threw the vessel is exempt from liability even though the vessel broke as a consequence of his actions. What is the reason? At the time that he threw the vessel, his arrows were stopped, i.e., what he did at the time he threw the vessel, which is an act comparable to the shooting of an arrow, did not have the capacity to break the vessel. Therefore, he is not viewed as having broken the vessel, and is exempt.

And Rabba says: If one threw a child from a roof and another came along and impaled him on his sword and the child died, the question of who is liable to receive the death penalty for killing the child is dependent upon the dispute between Rabbi Yehuda ben Beteira and the Rabbis. As it is taught in a baraita: If ten people beat a victim with ten sticks, whether they did so simultaneously or sequentially, they are all