Gemara

If an ox gored a half-slave on a day when he works for his master, the master receives damage payments. If it was on his own day (when the half-slave works for himself), he keeps the payments.

Question (Beraisa): If Reuven's ox (a Mu'ad, an established gorer) killed a half-slave, Reuven pays half of the fine (for a slave killed by a Mu'ad) to the master, and half the Kofer (paid for a free man killed by a Mu'ad) to the half-slave's heirs.

We do not say that if he was gored on the master's day, the master gets the full fine, and if it was on the slave's day, his heirs get the full Kofer!

Answer: The division of days applies only to earnings. This case is different, for the principal (the slave) was consumed (died)!

Question: Above, the one whose day it was receives payments for damage. In what case does damage not (at least partially) consume the principal?

Answer: His hand was stricken. It shriveled, but later it will heal fully.

Question: This is like Abaye, who says (Bava Kama 86a) that a man who inflicts such a wound pays both Nezek (the decrease in the slave-market value of the victim) and Sheves (compensation for inability to work until he recovers).

Rava (there) holds that he pays only Sheves. The owner of an animal that gored pays only Nezek. How can Rava answer?

Answer #2: The case is, a man wounded the half-slave.

Answer #3: Amora'im taught that the payment goes to the one whose day it was. Rava disagrees.

Bava Metzi'a 77a (Rava): If Reuven hired workers for the day and they finished the job in the middle of the day, if the only other work he has is harder, he cannot force them to do it, he must pay their full wage.

Question: He should pay them only like idle workers (for the rest of the day)!

Answer: Rava discusses workers that carry burdens. If they are idle from work, they grow weak.

Rishonim

Rif and Rosh (Bava Kama 31a and 8:6): Nezek is the value of his hand. Abaye does not mean the difference of his value with a hand and without. Rather, it is the difference between his value before and after his hand shriveled. Sheves is how much he could have earned (during the time he could not work, had he been healthy) guarding gourds. We already compensated for the inability to use his hand. Rava holds that Sheves is how much he lost from lost from not doing his normal job, for he is not compensated for the shriveling of his hand. The Halachah follows Rava.

Rebuttal (R. Yehonason, in Shitah Mekubetzes Bava Kama 86a DH u'Fosak): In Gitin we conclude like Abaye, and say that Rava disagrees with the teaching about an ox that gored a half-slave.

Note: This is not among the six Halachos (for which the acronym is YA'aL KeGaM) in which the Halachah follows Abaye against Rava! Perhaps R. Yehonason holds that it was not listed because other Amora'im are involved, i.e. the author of the teaching about a half-slave.

Rif and Rosh (ibid.): Presumably, he receives Sheves like an idle worker (how much one would want to be paid to be idle, rather than toil at his job).

Ran (DH Demei): Rashi says that Rava holds that Sheves is the amount that workers are paid in the market each day.

Me'iri (86a DH ul'Inyan): The Yerushalmi says that he receives his full normal wage. This is because he would prefer to work than to be idle and injured.

Rashba (86a DH Demei): He is paid like an idle worker. However, one who carries burdens weakens if he does not work, so he prefers working, and he is paid his full wage.

Rosh: All payments of Sheves are like an idle worker.

Rambam (Hilchos Chovel u'Mazik 2:11): If a limb was not lost, just he fell sick and was bedridden, or if his hand shriveled, but later it will heal fully, the damager pays Sheves for each day like a worker idle from that job.

Question (Tosfos R. Peretz 86a DH v'Rava): Nezek is the decreased value due to inability to use his hand until it recovers. Rava agree that he is compensated for this in Sheves. Practically, what do Abaye and Rava argue about?

Answer #1 (R. Peretz): Paying Nezek weakens the Nizak (injured party), for people overestimate how long the hand needs to recover. One who buys such a slave will pay little.

Note: Here, 'weakens the Nizak' does not mean that he collects too little. He collects more (because his sale value after the injury is low)! It must mean that paying Nezek is inaccurate, for the Nizak is weak in the eyes of people.

Answer #2 (Tosfos Rid 86a): Even if we estimate Sheves and pay the entire amount immediately, perhaps one who buys a slave would not deduct so much from the price, for he is sure that he will recover. Or, perhaps one who buys a slave would deduct more, for the slave will be unable to work for a long time.

Rosh (Bava Metzi'a 8:4): If one rented an animal and through his negligence its foot was bruised and will later recover, Tosfos says that he is exempt. The Halachah follows Rava that one pays only Sheves for such damage, and Sheves is not paid for animals. If so, when the Gemara discusses paying for weakening an animal, we must say that it will never recover. Others say that regarding people it is considered Sheves, for people are not normally sold, but animals are normally sold, so it is Nezek. Also, people are sold for much money, and (proportionally) one would not deduct so much for such injuries. One would deduct much from the sale of an animal.

Poskim

Shulchan Aruch (CM 307:6): If one rented an animal and through his negligence it was bruised and will later recover, some exempt because this is Sheves, and Sheves is not paid for animals. Some obligate paying.

Beis Yosef (DH Kosav Adoni): Here the Tur did not favor either opinion. In Siman 340, he rules like the first opinion.

Rema: The first opinion is primary.

Shulchan Aruch (CM 420:17): If a limb was not lost, just he fell sick and was bedridden, or if his hand shriveled, but later it will heal fully, the damager pays Sheves for each day like a worker idle from that job.

Tur: This depends on the job. Some jobs are strenuous and pay a little. For a small amount, one would agree to be idle from it. Some jobs are easy and pay much. One would agree to be idle from it only for a large amount.

SMA (20): The Rambam (Hilchos Sechirus 9:7) says that one who carries burdens or similar workers who weaken if they do not work is paid his full wage.

Yam Shel Shlomo (Bava Kama 8:14): The Rif says that when there is no Nezek and one pays only Sheves, he pays only like a worker would accept to be idle. It is only Garmi, therefore we are lenient. When one also pays Nezek, since we were lenient to evaluate Nezek only like a slave sold in the market, we are not lenient about Sheves, and he pays the full amount the injured party will earn when he recovers.