Arachin, Chapter 2, Mishnah 4. The previous mishnah taught the twelve days of the year on which the flute was sounded before the altar. Our mishnah asks the natural follow up question: who were the musicians? Three Tannaim answer, and their dispute turns out to hinge on a surprising point: how much can we learn about a man's family background from the fact that he was permitted to play in the Beit Hamikdash?
The Opinion of Rebbi Meir
The mishnah begins: "ve'avdei hakohanim hayu, divrei Rebbi Meir", the flute players were the Kena'ani slaves belonging to the kohanim. This is Rebbi Meir's view.
Rebbi Meir holds that permission to play an instrument in the Beit Hamikdash proves nothing whatsoever about a person's Jewish status or his fitness to marry into a Jewish family. Since no one would ever draw such a conclusion, the Chachamim had no reason to bar a Kena'ani slave, who may not marry a Jewish woman, from taking part in the music of the Mikdash.
The Opinion of Rebbi Yose
The second position belongs to Rebbi Yose: "mishpechot Beit Hapegarim u'Veit Tzeparya u'me'Emaom hayu masi'im likehunah". The musicians, in his view, were drawn from three prominent groups: the family of Beit Hapegarim, the family of Beit Tzeparya, and the people of a place called Emaom. All of them were Yisraelim of spotless pedigree, so much so that kohanim took wives from among their daughters.
For Rebbi Yose, the very fact that a man played in the Beit Hamikdash could later be cited as evidence of his pure lineage. Precisely for that reason the Chachamim would never have allowed a Kena'ani slave near these instruments. Only a Jew whose ancestry was beyond question, like the members of these families, was given the role.
The Opinion of Rebbi Chananya ben Antignos
A third position is recorded in the name of Rebbi Chananya ben Antignos, who maintains "Levi'im hayu": the men holding the instruments were Levi'im.
This tanna pushes the logic one stage past Rebbi Yose. To his mind, a bystander who watches someone play in the Mikdash will draw two conclusions, not one: not merely that the man's family line is clean, but that he belongs to shevet Levi, with the practical result that Ma'aser Rishon may be handed to him. Because such weighty consequences follow from that sight, the Chachamim limited the playing to genuine Levi'im.
What Everyone Agrees About
The dispute concerns the instruments alone. As for the singing in the Beit Hamikdash, there is no machloket at all: all three opinions agree that the song was performed by the Levi'im. This is not a matter of inference but of explicit pesukim.
"ve'sheret beshem Hashem Elokav kechol echav haLevi'im"
He shall minister in the Name of Hashem his God, like all his brothers the Levi'im. What is this service, this sheret? The word is understood as pointing to shirah, to song. From here we learn that the singing in the Beit Hamikdash belonged to the Levi'im, a point on which every Tanna in our mishnah concurs.