1) "ROVIM" AND "PIRCHEI KEHUNAH"
OPINIONS: The Mishnah (25b) says that "Rovim" perform Shemirah in the Beis Avtinas and the Beis ha'Nitzotz. The Mishnah later says that that "Pirchei Kehunah" sleep on the ground of the Beis ha'Moked. The Gemara asks that since both groups refer to young Kohanim, why is one called "Rovim" and the other "Pirchei Kehunah"?
The Gemara answers that Kohanim who are not "coming to perform the Avodah" are called "Rovim," and Kohanim who are coming to perform the Avodah are called "Pirchei Kehunah."
The Rishonim explain this answer in several ways.
(a) RABEINU GERSHOM and the MEFARESH explain that Kohanim under the age of thirteen, who are too young to perform the Avodah in the Beis ha'Mikdash, serve as guards for the Beis ha'Mikdash. These young Kohanim are called "Rovim" (as in "Ravya" -- "child"; see Chagigah 13b). When they reach the age of thirteen, they are called Pirchei Kehunah, since they are able to perform the Avodah in the Beis ha'Mikdash.
(b) The BE'ER SHEVA and the MISHNEH L'MELECH challenge the explanation of Rabeinu Gershom and the Mefaresh. How could this important obligation of Shemirah be left in the hands of minors? They explain instead that the minimum age for Kohanim was much older than thirteen.
The Rambam (Hilchos Klei ha'Mikdash, based on Chulin 25a) rules that although, technically, Kohanim were allowed to perform the Avodah from the time age of thirteen, their fellow Kohanim would not permit them to perform the Avodah until they reached the age of twenty. The Be'er Sheva and Mishneh l'Melech explain that the Rovim were above the age of thirteen, but they could not perform the Avodah since they were not yet twenty. The Pirchei Kehunah were the young Kohanim who were over the age of twenty.
(c) Rabeinu Gershom (27a) and the RAMBAM (Perush ha'Mishnayos) suggest another explanation. They explain that the words "Rovim" and "Pirchei Kehunah" refer to the same Kohanim. When discussing the first half of the night, the Mishnah calls them "Rovim," because at that time of day no Avodah is performed. When discussing the second part of the night, when morning approaches and the Kohanim prepare for the Terumas ha'Deshen, the Mishnah calls them "Pirchei Kehunah," since the time for performing the Avodah has arrived.
2) "KIL'AYIM" IN THE "BIGDEI KEHUNAH"
QUESTION: The Mishnah (25b) says that the Kohanim do not sleep in the Bigdei Kehunah. The Gemara infers from the Mishnah that only sleeping in the Bigdei Kehunah is prohibited (because it is disgraceful), but the Kohanim are permitted to walk around in the Bigdei Kehunah while they are not performing the Avodah, even though the Kohanim thereby derive personal benefit from them.
The Gemara rejects this inference and says that perhaps even walking around in the Bigdei Kehunah is prohibited. The reason why the Mishnah mentions only sleeping in the Bigdei Kehunah is that it wants to teach that when the Kohanim remove their vestments, they may place them beneath their heads. The Gemara asks that this itself is proof that the Kohanim may derive benefit from the Bigdei Kehunah, since they may rest their heads on them! The Gemara replies that the Mishnah does not mean that they are permitted to place the Bigdei Kehunah directly beneath their heads, but rather they may place them next to their heads.
The Gemara supports this interpretation of the Mishnah by pointing out that if the Mishnah means literally under their heads, then there would be a different problem of deriving benefit from Kil'ayim (for the Avnet was made of wool and linen).
Why does the Gemara address the problem of Kil'ayim only at this point? If there is a problem wearing the Bigdei Kehunah because of Kil'ayim, then why does the Gemara suggest at the beginning of the Sugya that the Kohanim are permitted to wear the Bigdei Kehunah even when they are not doing the Avodah? Even if there is no Isur of Me'ilah, there still is an Isur of Kil'ayim! Why does the Gemara address the problem of Kil'ayim only now, when it discusses placing the Bigdei Kehunah underneath one's head?
(a) TOSFOS in Menachos (40b-41a, DH Techeles) and the TOSFOS YESHANIM in Yoma (69a) point out that there is strong proof from this Sugya for the opinion of RABEINU TAM. Rabeinu Tam asserts that since one is permitted to wear a garment with Kil'ayim in order to fulfill the Mitzvah of Tzitzis, he may wear that garment even at a time when no Mitzvah is being fulfilled (such as at night). (Rabeinu Tam maintains that the reason why one is permitted to wear a garment with Kil'ayim in order to fulfill the Mitzvah of Tzitzis is not merely because of the principle of "Aseh Docheh Lo Ta'aseh," but because the Torah completely permits ("Hitirah") the Isur of Kil'ayim on a garment with Tzitzis.) A similar principle may be applied to wearing Kil'ayim in the Bigdei Kehunah. Since the Kohen is permitted to wear Kil'ayim while he is performing the Avodah, he also may wear the Bigdei Kehunah with Kil'ayim while he is not performing the Avodah. The Isur of benefiting from Kil'ayim applies only when the Kohen is not wearing the Bigdei Kehunah, but is warming himself with them in another manner. The Torah permits Kil'ayim only when the Kohen is wearing the Bigdei Kehunah, but not when he is sitting on top of the Bigdei Kehunah or resting his head on them.
(See also RA'AVAD, Hilchos Kil'ayim end of ch. 10, and Hilchos Klei ha'Mikdash 8:10, who rules like Rabeinu Tam and argues with the Rambam on this point.)
(b) The MEFARESH here says that the Gemara's question of Kil'ayim does refer back to the beginning of the Sugya, and the Gemara indeed could have asked it there. The Gemara, however, knew that the answer to the question would apply to the entire Sugya, to all of the cases of wearing the Bigdei Kehunah with Kil'ayim. The Gemara later quotes Rav Ashi who answers that the garment with Kil'ayim is made of a very hard material, to which the Isur of Kil'ayim does not apply.
The Mefaresh learns that not only is the Kohen permitted to lie on Kil'ayim when the garment is made of a hard material, but there is also no problem of wearing Kil'ayim when the garment is made of a hard material, because it does not warm the person while he wears it. Since it does not serve to warm him, it is not a prohibited act of wearing Kil'ayim. (See also Insights to Yoma 69:1 and 69:3.)
3) PLACING TEFILIN NEXT TO ONE'S BED
QUESTION: The Mishnah (25b) says that the Kohanim would not sleep in the Bigdei Kehunah. Rather, they took them off and placed them beneath their heads as pillows. The Gemara attempts to prove from here that the Kohanim are permitted to derive benefit from the Bigdei Kehunah while not performing the Avodah. The Gemara refutes this proof and says that the Mishnah means that the Kohanim placed their vestments next to their heads, and not directly beneath them.
Rav Papa infers from here that one is permitted to place Tefilin next to his bed while he sleeps, and there is no concern that he might roll over onto his Tefilin while he sleeps. The MEFARESH (DH Amar Rav Papa) explains that the proof is from the fact that the Kohen is permitted to place the Bigdei Kehunah next to his head when he sleeps (as long as he did not place them directly beneath his head), even though the Torah prohibits deriving benefit from the Bigdei Kehunah at any time other than when performing the Avodah. The Chachamim did not prohibit the Kohen from placing the Bigdei Kehunah there lest he roll over and derive benefit from them and transgress the Isur d'Oraisa of Me'ilah. Accordingly, we certainly do not prohibit sleeping next to one's Tefilin, because even if one would roll over onto the Tefilin, he would not transgress an Isur d'Oraisa but only an Isur d'Rabanan of disgracing Tefilin. The Mefaresh adds that the Tefilin must be placed between the "Kar" and the "Keses," but not directly under his head. As the Gemara in Berachos (24a) explains, the Tefilin should protrude slightly (in their bag) from beneath one's pillow, so that they are not directly under one's head.
The Gemara here, however, seems to contradict the practical Halachah as recorded by the SHULCHAN ARUCH. The TALMIDEI RABEINU YONAH in Berachos (15a of the pages of the Rif) write that even though the Halachah is that one is permitted to place the Tefilin underneath his pillow as long as they are not directly under his head, one should be stringent and not place them in the bed itself at one's side, just as the Gemara there (end of 23b) concludes that one may not place them under one's feet as this is disgraceful for the Tefilin. Rabeinu Yonah states that the reason why one may not place the Tefilin in the bed at his side is that a person occasionally rolls over in his sleep and he might roll over onto the Tefilin, causing a disgrace to them. This view is recorded as the Halachah by the Shulchan Aruch (OC 40:5), who writes that one must not put Tefilin at his side in the bed, just as one may not put them under his feet.
The Shulchan Aruch clearly rules that we are concerned that one will roll over on top of his Tefilin as he sleeps, while the Gemara here clearly says that there is no such concern! How is the ruling of the Shulchan Aruch to be reconciled with the Gemara here?
(a) The BI'UR HALACHAH (OC 40:5, DH ul'Hanicham) first suggests that since the RAMBAM (Hilchos Klei ha'Mikdash 8:11) rules that one is permitted to derive benefit from the Bigdei Kehunah, it follows that Rav Papa's statement is not relevant in practice, because even if one would roll over onto the Bigdei Kehunah he would transgress no Isur.
However, the Bi'ur Halachah rejects this answer. It is evident from Rav Papa's logic that if there would be any concern about rolling over onto the Tefilin, then one would be prohibited to place the Tefilin next to his head. Therefore, since the Halachah is that one may place the Tefilin next to one's head but not directly underneath, it follows that there is no concern that one will roll over onto them. Accordingly, the Gemara here still appears to contradict Rabeinu Yonah's ruling that one may not place the Tefilin at one's side when he sleeps.
(b) Perhaps there is a difference between placing Tefilin between two cushions or sheets ("between the Kar and the Keses") and placing Tefilin next to one's bed, uncovered. When the Tefilin are placed between the Kar and the Keses, there is a lesser likelihood that they will find their way under the person sleeping. When the Tefilin are next to him, uncovered, there is a greater concern that he will turn over and sleep directly on the Tefilin. Therefore, Rabeinu Yonah and the Shulchan Aruch rule that one may not place Tefilin next to oneself in the bed.
(It should be noted that it is apparent from the Gemara in Berachos (25a) and RASHI there (DH Kol) that the Chachamim permitted placing the Tefilin only near one's head, in order to protect them from mice and thieves. Accordingly, the MISHNAH BERURAH (OC 40:11) writes that if another safe place is available, one should not place the Tefilin in the bed at all. If there is a shelf either three Tefachim above or below the head of the bed, then one is permitted l'Chatchilah to place the Tefilin there.) (D. BLOOM)