Chapter 4, Mishnah 7 (in some versions this mishnah is numbered differently). The author of the teaching before us is Rabbi Tzadok, familiar from the Gemara: when Rabban Yochanan ben Zakkai made three requests of Vespasian, one of them was that medical care be given to Rabbi Tzadok. Rabbi Tzadok is the tzaddik who sat for some forty years at the gates of Jerusalem and fasted every day, in order to bring merit to Israel and prevent the destruction - which in the end took place nonetheless. He was a kohen and a tremendous tzaddik, and although he was among the students of Beis Shammai, he always ruled like Beis Hillel. In our mishnah too he quotes Hillel explicitly, and even where he does not quote him, he expresses Hillel's approach.
It is worth noting that there are versions that attach to this mishnah portions of the earlier mishnayos in the chapter as well. Our version does not include them, and even if it would have been appropriate to attach them, we have already discussed those portions in their own place.
The text of the mishnah:
Rabbi Tzadok says: "Al ta'asem atarah lehisgadel bahem, velo kardom lachpor bahem" - do not make them a crown with which to aggrandize yourself, nor a spade with which to dig. The word "them" in the mishnah refers to words of Torah: one may not make words of Torah into a crown with which a person glorifies himself, nor a spade with which to dig.
The word "kardom" is sometimes translated as a digging spade, but its precise meaning is an axe. It seems that this itself contains a point: for digging, an axe is a poor choice of tool. The mishnah deliberately uses the tool that is unsuited to the task, to teach us that the Torah is not a crown to take pride in, nor is it a tool by means of which a person should earn his living.
"Vechach hayah Hillel omer" - and so Hillel used to say:
Rabbi Tzadok continues and quotes Hillel, who lived some hundred years before the destruction: "Udeyishtamesh betaga chalaf" - and one who makes use of the crown passes away. This is a quotation from the mishnah in Chapter 1, Mishnah 13. The language is Aramaic: "taga" means a crown (and as we mentioned there, the Mikraos Gedolos of the Yemenites is called a "Taj"), and "chalaf" means he will pass away. That is, one who makes use of the crown of Torah will pass away. Some explain that he will die before his time, and some say that he loses his share in the World to Come.
From here Rabbi Tzadok draws an explicit conclusion: "Mikan atah lamed, kol hanehneh midivrei Torah - notel chayav min ha'olam" - from here you learn that anyone who derives benefit from words of Torah takes his life from the world. Anyone who derives personal benefit from words of Torah - whether as a crown, for his own personal honor, or as a spade, as a tool with which to earn a living - takes his life from the world. Many explain that this means he dies before his time, and many others, among them Rashi and the Rambam, explain that it refers to the World to Come.
It emerges from the mishnah that the Torah was given in order to be learned and to be fulfilled. Using it as a crown, as a means of self-glorification and so that people should call him "Rabbi" and the like, is an extremely serious matter, and there is in it something of a misuse of what is holy. Rabbi Tzadok says more than this: do not even make words of Torah into a tool for your livelihood, a spade with which to dig - that is, that your livelihood should come from serving as a rav, as a rosh yeshivah or as a dayan.
Two points that must be stated first:
The first: there is the well known Gemara in Pesachim that a person should begin his involvement in mitzvos even not for their own sake, since through doing them not for their own sake he will come to do them for their own sake. This applies to a young person who does not yet understand, and this is human nature: a child needs an incentive, and acting from the right reasons - the Shema and the love of Hashem, as we explained in its place in the tractate - is too abstract for him. Therefore we begin by giving an incentive. But all of this is on condition that his intention is ultimately to reach acting from the right reasons. A person who is driven by the wrong reasons with no intention of reaching lishmah will never arrive there. We see many people who learn Torah and keep mitzvos for the wrong reasons, and never reach lishmah. There must be an intention to arrive at lishmah, and this is not the subject of our mishnah.
The approach of the Rambam:
The second observation: the Bartenura here explains according to the approach of the Rambam, which is famous for holding that a person has no room whatsoever to make personal use of the Torah. The Rambam even speaks harshly about a person who intends to be a Torah scholar supported by charity funds - what we would call today learning in kollel.
These are his words in Hilchos Talmud Torah, chapter 3, halachah 10: "Anyone who sets his heart to occupy himself with Torah and not to work, and to support himself from charity - he has desecrated God's Name, degraded the Torah, extinguished the light of the faith, brought evil upon himself, and taken his life from the World to Come". In other words, someone whose plan is this - to be a full-time Torah learner, not to work, and to be supported by the community - transgresses the desecration of God's Name, which is the most severe of sins, as we discussed in the previous mishnayos, because he causes the public not to take the word of God seriously. Beyond that, he degrades the Torah, extinguishes the light of the faith, causes irreversible damage to himself, and takes away his life not only in this world but even in the World to Come - and the Rambam uses the language of our mishnah with the addition of the words "World to Come".
The Rambam continues and gives the reason: "Because it is forbidden to derive benefit from words of Torah in this world" - a sweeping prohibition against receiving any benefit whatsoever from words of Torah in this world. He then quotes our mishnah: "The Sages said: Anyone who derives benefit from words of Torah has taken his life from the world", and also "Do not make them a crown with which to aggrandize yourself, nor a spade with which to dig". And he adds: "They further commanded and said: Love work and hate rabbinic office" - a person should love labor and hate rabbinic office. And in conclusion: "And any Torah that is not accompanied by work will in the end be nullified and will drag along sin, and such a person will ultimately rob people" - one who does not support himself through work will find that the Torah itself is ultimately nullified and lost to him, and it drags him into sin, until in the end he robs people.
This is of course an extremely severe accusation, but this is the approach, based primarily on our mishnah and on the mishnayos we mentioned earlier, and the Baal HaTurim explains it this way as well. According to the Rambam there is no permission at all to receive payment for being a teacher, a rabbi, a rosh yeshivah and the like.
How, then, do teachers and judges receive payment?
The Gemara itself recognizes a reality in which people sit and teach and receive payment for it, and it resolves this with two basic approaches:
Payment for an accompanying service: The teacher does not receive payment for transmitting the Torah itself, but for watching the children so they come to no harm, for training them in good character traits, and for seeing to it that they learn to read - matters that are not part of transmitting Torah as such. The foundation of this is learned from the verse, that Moshe Rabbeinu taught the Torah without charging payment: "Ra'eh limadti eschem chukim u'mishpatim ka'asher tzivani Hashem Elokai" - "See, I have taught you statutes and laws as Hashem my God commanded me", and the Sages expounded: "Mah ani b'chinam - af atem b'chinam" - just as I taught for free, so too you must teach for free. Just as Moshe Rabbeinu taught without payment, so every person must transmit the tradition without charging. According to this approach, the teachers in Talmud Torahs and the rebbeim receive payment for something other than the teaching of Torah.
Compensation for lost time: A person who sits as a judge is permitted to receive s'char batalah - compensation for the fact that he is not engaged in other work.
This is how the Rambam explains it, and it is worth noting that the Rambam himself was a devoted community rabbi all his life, and his life was complicated; yet he never took a penny for any service he provided to the community as a judge, as a rabbi, or the like.
The approach of the Kesef Mishneh:
By contrast, the Kesef Mishneh - that is, Rabbi Yosef Karo, the author of the Shulchan Aruch, whose first major work was the Kesef Mishneh, in which he went through the Rambam from beginning to end, corrected the text, identified the sources and discussed them - disagrees forcefully with the Rambam. In his words, this is how it has always been: there were rabbis and Torah leaders in communities who were supported by charity, and this is the way the matter has been done. And even if the Rambam is right and in theory it is not proper, in practice this falls under the principle of "it is a time to act for Hashem". We have no choice in the matter, because if we did not pay the rabbis, the teachers, the roshei yeshivah and the judges, they would not be able to engage in this work, and we would have no teachers and no roshei yeshivah - and we would not be able to transmit the Torah and the tradition.
In summary: This is the famous dispute between the Rambam and the Kesef Mishneh, and it is not for us to decide between them. But the straightforward approach in this mishnah, and certainly that of the Bartenura, is that a person may not seek to use the Torah in any form whatsoever - neither for his personal glory nor as a way of earning a living from it at all.