Gemara

76b Levi was Metzamtzem Yehudah's animals in the sun. They died. Ravina obligated him to pay, due to a Kal va'Chomer:

A murderer is liable only if he killed intentionally and willingly, and not if he was Shogeg or Ones, yet Metzamtzem is liable. A damager pays whether he damaged Mezid or Shogeg, willingly or Ones, so all the more so he is liable for Metzamtzem!

Makos 2a (Mishnah): If witnesses testify that a Kohen is a Chalal (Pasul) and they were Huzmu, they do not become Chalalim. Rather, they receive 40 lashes.

(R. Yehoshua ben Levi): We learn from "va'Asisem Lo Ka'asher Zomam" - to him, but not to his descendants. (If the witness would become a Chalal, this would disqualify his descendants.)

5b (Mishnah): "Va'Asisem Lo Ka'asher Zomam La'asos l'Achiv" connotes that the Nidon is still alive.

(Beraisa - Beribi): If they did not kill, they are killed. If they killed, they are not killed. Ein Onshim Min ha'Din!

(Beraisa): "V'Ish Asher Yikach Es Achoso Bas Aviv Oh Vas Imo" obligates for a paternal or maternal sister. "Ervas Achoso Gilah" obligates for a full sister (from both parents)!

Since a verse must teach this, this shows that Ein Onshim Min ha'Din.

Bava Basra 56a (Mishnah): If two witnesses testified that Reuven ate the Peros of Shimon's field for three years, and they were Huzmu, they pay Shimon the entire value of the field.

Bava Kama 74a (Beraisa): If two said 'we testify that Ploni knocked out his slave's tooth, then blinded his eye. Behold, the slave says so', and they were Huzmu, they pay the value of his eye to Ploni.

Question: If the latter witnesses (the Mazimim) do not testify that Ploni hurt his slave, the first witnesses tried to improperly make the slave go free. They should pay the master his full value!

Rishonim

Rambam (Hilchos Edus 20:2): If the Nidon was killed and afterwards the witnesses were Huzmu, we do not rely on a Kal va'Chomer to kill them. It says "Ka'asher Zomam", i.e. they did not yet do it. However, if money was transferred, it is returned, and the witnesses pay him.

Kesef Mishneh: What is the Rambam's source to distinguish money from Misah? Seemingly, "like they plotted, not like they did" should apply also to money. One could say that since money can be returned, there is no difference between plotting and doing, like Tosfos (brought below) says.

Tosfos (Bava Kama 4b DH v'Edim): The Riva says that even if the Nidon paid due to the false testimony, the witnesses must pay. "Like they plotted, not like they did" does not apply to money, for it can be returned. The Ri says that we do not need this reason, for regarding money, Onshim Min ha'Din.

Radvaz: "Va'Asisem Lo Ka'asher Zomam La'asos l'Achiv" connotes that the Nidon is still alive. Therefore, we do not punish after he was killed, but we punish after he paid. This requires investigation. Alternatively, regarding money, Onshim Min ha'Din. The Nidon acquires the fine just like the victim of theft acquires Kefel (double payment).

Nimukei Yosef (Bava Basra 30a DH Meshalmin): The Ritva asked, why do the witnesses about the field pay? They can become Zomemim only after a final verdict. Once we ruled that the field is Reuven's, this is 'like they did, not like they plotted' (so we cannot punish them)! We must say that Reuven (the Machazik) was not in the field when they were Huzmu.

Mishneh l'Melech (21:4): The Ritva requires "like they plotted, not like they did" also for money. However, when witnesses say "the master knocked out his slave's tooth, and afterwards blinded him" (and they were Huzmu), why do they pay for the slave (Bava Kama 73b)? Once we ruled that the slave is free, he seizes himself, and this is 'like they did'. It is not "like they plotted"! This requires investigation. The slave needs a Get Shichrur (document of freedom) only to permit him to marry a Bas Yisrael, but even without this, the master cannot force him to work.

Tumim 38 (85:4): Until he gets a Get Shichrur, the matter is not finished, even though he seized himself. According to the Ritva, why did the Gemara assume that the witnesses should pay the full value of the slave? Perhaps the Beraisa holds like the opinion that no Get Shichrur is needed, so he is already free, so the witnesses are exempt for this! We can say that the Gemara asked a big question (the witnesses should need to pay the slave's full value) according to the Halachah, even though there is an easy answer to part of the question. Further, as long as the master did not pay for the tooth or eye, the case was not finished.

Kovetz Shi'urim (Bava Basra 249): Tosfos (Gitin 17a DH Mipnei) says that a slave seizes himself when there is a Safek if he was freed (before he was sold) and (perhaps) he acquired a Yad to seize himself. Here, the Hazamah reveals that he was never freed.

Tiferes Yisrael (Bava Basra 3:4, Boaz 1): The Rambam rules that the slave cannot collect from one who damaged him until he gets a Get from his master. This shows that he does not seize himself until then. The question from Chazakah is not difficult. Land is in the Chazakah of its owner.

Tumim (ibid.): A proof for the Rambam is Hazamah of testimony about a Chalal. The matter is done once Beis Din accepts the testimony, yet the witnesses are lashed! Do not say that the Kohen accepted money for Pidyon Bechor, and the witnesses were Huzmu before he returned it. If so, the witnesses would not be lashed, for they must pay. (Note: if the witnesses could say 'we did not know that he received Pidyon money. We sought only to disqualify him', then the matter they plotted about was done - PF). However, why must a verse teach that witnesses do not become Chalalim? This is obvious, for the matter was finished! Rather, the verse is needed for when they testified that Ploni is a Mamzer or Mitzri and he must divorce his wife, and he did not yet do so. Also, the Torah requires Drishah v'Chakirah (interrogation of witnesses) for monetary cases, i.e. it must be Efshar Lehazimah. We cannot punish witnesses about payment or a receipt, for the matter is finished immediately! We could answer like the Rivash (266), who says that Edim Zomemim are disqualified even if the Mezimim testified before the verdict. However, it is difficult to say that this suffices to consider the testimony Efshar Lehazimah.

Aruch l'Ner (Makos 2b DH Aval): We distinguish between "like he plotted" and 'like he did' only when there is a difference between the final verdict and what happens afterwards. When there is no Ma'aseh afterwards, this is called Ka'asher Zomam, and not 'like he did.' This answers also the question from Chalal.

Kehilas Yakov (Bava Kama 3, Makos 6): Testimony for someone to keep his property need not be Efshar Lehazimah. Regarding money, 'not like they did' is when their scheme caused someone to be Muchzak improperly. A slave is Muchzak in himself even without their testimony. Their testimony exempts him from working, and this is not finished yet, for the master can still demand that he work and to receive his earnings.

R. Akiva Eiger (1:176 DH uv'Ikar): Whether regarding money we do not say "and not like they did", like Tosfos says, or if we exempt them from paying after the Nidon paid, in any case the witnesses are lashed for Lo Sa'aneh. No verse exempts from lashes, so the testimony is Efshar Lehazimah, like Tosfos (2a DH Me'idim) says. We must say so, for witnesses of Chazakah help even if the Machazik (the alleged buyer) is in the land, like it says 'what are you doing on my land?' How else could we answer for those who require testimony that is Efshar Lehazimah even after the enactment (not to require Drishah v'Chakirah for monetary cases)? Once there is a verdict, it was carried out (the land is his)! Likewise, if witnesses testified that an ox must be stoned, and they were Huzmu, they pay or are lashed. Do not say that we must kill the ox like we (would) kill the owner, and the testimony must be Efshar Lehazimah regarding Misah, i.e. the witnesses can be killed. If so, even if they pay, how can we kill the ox? Rather, to kill the ox we do not require Efshar Lehazimah, since it is never possible. Therefore, even if the witnesses need not pay due to 'not like they did', we judge just on the ox. The witnesses obligate it to die.

Noda b'Yehudah (1 EH 72 DH Od): We do not require Efshar Lehazimah for monetary cases. This is why the Nimukei Yosef did not ask how Chazakah is possible if the Machazik is there. He only asked why the witnesses must pay. We hold that monetary witnesses need not testify together. The first witness is exempt for Hazamah, for he can say 'I did not know that another witness would come. I came only to obligate an oath.'