וְהַכֹּהֵן֩ הַגָּד֨וֹל מֵאֶחָ֜יו אֲֽשֶׁר־יוּצַ֥ק עַל־רֹאשׁ֣וֹ ׀ שֶׁ֤מֶן הַמִּשְׁחָה֙ וּמִלֵּ֣א אֶת־יָד֔וֹ לִלְבֹּ֖שׁ אֶת־הַבְּגָדִ֑ים אֶת־רֹאשׁוֹ֙ לֹ֣א יִפְרָ֔ע וּבְגָדָ֖יו לֹ֥א יִפְרֹֽם׃
At ang saserdoteng pinakadakila sa kanyang mga kapatid, na ang ulo ay binuhusan ng langis ng pagpapahid, at itinalaga upang magsuot ng mga kasuotan, ay hindi hahayaang humaba ang buhok ng kanyang ulo, at hindi niya pupunitin ang kanyang mga kasuotan;
Tze'enah Ure'enah
“The priest who is exalted above his fellows” [21:10]. The high priest must keep himself much holier than the ordinary priest. He should not become impure to any corpse, not even father and mother. He should not marry a widow or divorcee, but only a virgin. The reason that he should not marry a widow or divorcee is that he will accustom the virgin to sleeping with him as is appropriate for a high priest. He must maintain his holiness with his wife and the way he accustoms the virgin; she will accept it. However, when he marries a widow or divorcee who are used to sleeping with their first husband all the time, and she will touch the high priest to sleep with her all the time, which will lead the high priest to commit a sin. “The priest who is exalted above his fellows” [21:10]. He should be more important than the other priests in five ways. He must be a handsome man. He must also be strong, wealthy, wise, and have honor. When he is not wealthy, his brothers make him wealthy.9Bahya, Leviticus, 21:10.
Rashi
לא יפרע [THE HAIR OF HIS HEAD] SHALL HE NOT DISARRANGE — i.e. he shall not let his hair grow wild on account of ritual mourning for the death of a near relative (Sifra). And what is called "letting the hair grow wild”? Leaving it uncut for more than 30 days (Sanhedrin 22b).