Mishnah 3:5. In the previous mishnah we learned that the Kohen Gadol does not perform peri'ah and perimah - letting the hair grow and tearing the garments - as part of the customs of mourning. Our mishnah deals with two matters and how they apply to the Kohen Gadol: the mitzvah of perimah, that is, tearing the garments, and following from it, the laws of aninus. We will explain them one after the other.
The mitzvah of tearing:
Tearing, the rending of a person's garments, is a rabbinic mitzvah that the Sages instituted out of recognition of the honor due to the deceased. Someone who has lost one of his seven relatives - mother, father, brother, sister, son, daughter or wife - must tear the front of his outer garment, from the neck downward or near the shoulder, a tear of a full handbreadth.
We have seen that the Kohen Gadol does not tear in the manner of everyone else. But since the reason for the mitzvah is the honor of the deceased, and so that people should know that this man has lost a relative, it is understandable that the prohibition on the Kohen Gadol is to tear in the usual way - the way that was customary in the times of Chazal, tearing the outer garment in front - yet the possibility of tearing itself was not entirely denied him.
And therefore the mishnah says: "Kohen gadol porem milmatah" - the Kohen Gadol tears his garments from below upward. According to most opinions this is not merely permitted but obligatory: he does it in honor of the deceased, only from below, and in this he is distinguished from everyone else, and that is enough. According to the Minchas Chinuch it is only permitted, not required.
"Ve'hedyot milmalah" - an ordinary kohen who has lost one of his seven relatives fulfills this mitzvah of tearing his garments from above, in the measure of a handbreadth. And if he tore from below or on the back of his garments, he has not fulfilled the obligation of the mitzvah.
The laws of aninus:
Who is an onen? A person who has lost one of the seven relatives for whom he is obligated to mourn becomes an onen by Torah law on that very day, until the emergence of three stars, and this entails several restrictions:
He is exempt from performing positive commandments, and therefore he does not recite a berachah, for example, after eating bread and the like.
He is forbidden to eat sacrificial food, and even Maaser Sheni.
In the case of an ordinary kohen, an onen may not even perform service in the Beis HaMikdash, and he must stop his service from the moment he learns of the loss of his relative. The status of aninus by Torah law ends with the first night after the relative's death, but by rabbinic law it continues until the night after the burial - a period that may last two or even three days. Throughout that time he does not perform the service and does not eat sacrificial food. It is worth noting that the exemption from positive commandments does not apply during rabbinic aninus.
And here the mishnah says: "Kohen gadol makriv onen ve'lo ochel" - the Kohen Gadol may perform the service and offer sacrifices while he is an onen, and the basis for this lies in the verses stated in connection with the discussion of Aharon the Kohen and Nadav and Avihu. Nevertheless, he may not eat from the meat of the sacrifice or from sacrificial food while he is an onen.
"Ve'hedyot lo makriv ve'lo ochel" - an ordinary kohen may not perform any service at all in the Beis HaMikdash, and certainly does not eat from the meat of sacrificial food as long as he is an onen. An ordinary kohen who heard about the loss of his relative in the middle of the service stops and hands the service over to another. Technically he must remain until that particular service is completed, and then he may leave, and indeed he is required to leave. And in fact, if he performed the service while he was an onen, that service is invalid, since this is a matter of me'ilah.
One final clarification: when we speak of the tearing of the garments of a kohen or of the Kohen Gadol, this does not refer to the priestly garments, but to their own private, personal clothing that they were wearing, whether or not they were dressed in the special priestly garments at the time.
In summary: In this mishnah we learned two laws concerning the Kohen Gadol. Regarding tearing - the Kohen Gadol tears from below and an ordinary kohen from above, since the reason for the enactment is the honor of the deceased, and therefore the Kohen Gadol was not denied the tearing itself, only its usual manner. Regarding aninus - the Kohen Gadol offers sacrifices while an onen but does not eat from the sacred offerings, whereas an ordinary kohen neither offers nor eats, and if he did perform the service, it is invalid.