(Mishnah): If Ploni received wages for ruling about a (Mum of a) Bechor, one may not rely on his ruling to slaughter it;

The only exception is an expert like Ila of Yavneh. Chachamim permitted him to receive four Isarim (an Isar is eight Perutos) for checking a small animal, and six Isarim for a large animal, whether he ruled that it is Tam or Ba'al Mum.

(Gemara) Question: Why did he receive more for a large animal?

Answer: It is more work to check its Mum (he must throw the animal to the ground and tie it up).

(Mishnah):... Whether he ruled that it is Tam or Ba'al Mum.

Question: Granted, he is paid for ruling that it is a Ba'al Mum. This permits it to be slaughtered;

Why is he paid for ruling that it is Tam?

Answer: If he were paid only for ruling that it is a Ba'al Mum, people would suspect that he does so even when it is really Tam, for his own profit.

Question: Now that he is paid either way, people might suspect that he forbids Ba'alei Mum (i.e. says that it is not a Mum) in order to profit, for the owner will bring it to him again after another Mum develops!

Answer: Chachamim enacted that he is paid only once for any one animal (even if he checks it many times before permitting it).

(Mishnah): If one was paid for any of the following Mitzvos, the Mitzvah is invalid:

To judge, to testify, to sprinkle Mei Chatas, or to be Mekadesh (to mix the ashes with the water);

The following compensation may be given;

If a Kohen became Tamei (in order to do a Mitzvah), one may give him Chulin to eat, drink and anoint with, for now he may not consume Terumah;

One may supply a donkey for an elder (who has difficulty walking) to ride on;

If a worker was idle from his job, one may pay him like a worker (this will be explained).

(Gemara) Question: What is the source (to forbid wages for giving rulings, i.e. teaching Torah)?

Answer (Rav Yehudah): "Re'eh Limadti Eschem... " - just like Moshe was not paid for teaching Torah, we should not be paid for it. (Rashi (Kidushin 58b) - one may not be paid for any Mitzvah that is not an exertion, for the wages are for having learned how to do the Mitzvah.)

Support (Beraisa): "... Ka'sher Tzivani Hash-m Elokai" (the end of the above verse) - just like Moshe taught Torah for free, we should do so.

Question: What is the source that if one cannot find a Rebbi to teach him for free, he should pay to learn?

Answer: "Emes Keneh."

Question: What is the source that one should not say "just like I had to pay to learn Torah, I will charge to teach"?

Answer: "Emes Keneh v'Al Timkor."

(Mishnah): If one was paid to sprinkle or to be Mekadesh the water, the water and ashes are not Metaher.

Contradiction (Mishnah): If one was Mekadesh a woman with the water or ashes (of Parah Adumah), she is Mekudeshes, even if he is a Yisrael. (Kidushin requires something worth money. This shows that one may charge for them!)

Answer (Abaye): One may not be paid to sprinkle or to be Mekadesh. (If he was, this disqualifies the water and ashes);

One may be paid for (and therefore make Kedushin with the act of) transporting ashes or filling up the Kli with water. (Rashi - this act is not the Mitzvah itself.)

Support: Our Mishnah disqualified one who was paid to sprinkle or to be Mekadesh. The Beraisa discusses Kedushin using the water and ashes themselves (Rambam; Rashi - the act of transporting them).

(Mishnah): If a Kohen became Tamei, disqualifying him from Terumah...

Question: A Kohen is forbidden to become Tamei (for these Mitzvos. He is permitted only for deceased relative or a Mes Mitzvah, i.e. a body that no one is is around to bury it)!

Answer #1: The Kohen passed through a Beis ha'Peras (a field in which a corpse was plowed. We are concerned lest the plow dragged bones.) Its Tum'ah is only mid'Rabanan. (We are concerned lest one who walks through touch or move a bone k'Se'orah (the size of a barley seed)):

(Rav Yehudah): One may walk through a Beis ha'Peras if he bendsng down and blows the earth (to clear away any small bones he might encounter) before each step. (If Tum'as Beis ha'Peras were mid'Oraisa, Chachamim would not allow this leniency, nor the next, for something that was definitely forbidden is not permitted due to a Safek, i..e perhaps the Tum'ah was removed.)

(Rav Yehudah bar Ami): If many people have walked through a Beis ha'Peras, it is Tahor. (We assume that any small bones have been crushed to less than k'Se'orah.)

Answer #2: The Kohen became Tamei through a Tum'ah that is not forbidden to him (any Tum'ah other than Mes. Some permit some kinds of Tum'as Mes to him.)

(Mishnah): One may supply a donkey for an elder to ride on. (If a worker was idle from his job, one may pay him like a worker.)

(Beraisa): One pays a worker the amount of compensation he would want to be idle from his job (for the time he engaged in the Mitzvah).

(Abaye): We account for the exertion of his job. (One who engages in light work would want almost his full wage to be idle (Tosfos; Rashi - to do the Mitzvah instead). One who engages in rigorous work would accept a small portion of his wages to be idle.)

(Mishnah): If Reuven is suspected to make a Mum in Bechoros (alternatively - treat Tam Bechoros like Chulin), one may not buy from him (what he says is) deer meat (for it looks like calf meat) nor untanned skins;

R. Eliezer permits buying skins of female animals.

One may not buy from him cleaned or dirty wool. One may buy spun thread or garments.

(Gemara): One may not buy deer meat because it looks like and can be confused with calf meat.

Inference: One may not buy untanned skins, but tanned skins are permitted;

If it really was a Bechor, Reuven would not bother (Rashi; Rambam - keep it long enough) to tan it, lest Chachamim find out and forbid it.

(Mishnah - R. Eliezer): It is permitted to buy skins of female animals.

Question: What is the reason?

Answer: It is evident (from the genital area) that it is a female, so Bechorah does not apply to it.

The first Tana disagrees. One could cut out the male genitals, and say that (it is a female, and that) mice nibbled there.

R. Eliezer holds that one would be able to tell that it was not mice.

(Mishnah): One may not buy cleaned or dirty wool.

Question: If one may not buy cleaned wool (even though he put effort into it), there is no need to forbid buying dirty wool!

Answer: It means, one may not buy wool cleaned from its dirt.

(Mishnah): One may buy spun thread or garments.

Question: Garments are already included in the Heter to buy spun thread!

Answer: The Mishnah permits felt garments. (They are not made from thread.)

(Mishnah): If Reuven is suspected about Shemitah (to plant, or do business with Shemitah produce), one may not buy from him flax, even if it was combed;

One may buy spun thread or Arig (woven material).

(Gemara) Question: Arig is already included in the Heter to buy spun thread!

Answer: The Mishnah permits chains made from unspun flax.

(Mishnah - R. Yehudah): If Reuven is suspected to sell Terumah and say that it is Chulin, one may not buy from him even water or salt;

R. Shimon forbids (only) anything to which Terumah applies.

(Gemara) Question: What does "anything" come to include?

Answer: It includes fish innards, for often olive oil is added.