פּירוש אויף ויקרא 21:5

לא יקרחו קרחה THEY SHALL NOT MAKE BALDNESS [UPON THEIR HEAD] for the dead. But were not the ordinary Israelites also forbidden in respect of this? Why then is this law especially stated with reference to the priests? But because in the prohibition addressed to the ordinary Israelites it is stated, (Deuteronomy 14:1) “[Ye shall not make anybaldness] between your eyes [for the dead]”, I might think that one is not liable to punishment for making baldness on any other part of the whole head, Scripture therefore states here: “upon their heads”; and now that we have both commands, the law regarding the Israelites may be derived from that addressed to the priests from a similarity of terms used in both prohibitions: the term “קרחה” is used here, and in the prohibition regarding the Israelites it also uses the term “קרחה”; what is the case here? The prohibition applies to the whole head! So, also, there the whole head is included in the prohibition. And, on the other hand, how is the case there? The prohibition is limited to making baldness for the dead! So here too it applies only to such baldness as is made for the dead (Makkot 20a; Kiddushin 36a).

They shall not make a bald spot on their head. Even though Israelites were also warned about this, nevertheless both [prohibitions] are necessary. For if we were only informed about Israelites, one might think that only [mourning for] the loss of an Israelite for his generation does not make such a significant impression, therefore one should not grieve excessively by making a bald spot for him, because he also does not make such a significant void in the world. But for a priest, who serves our God, who dies, certainly the loss is great for his generation and makes a void in the world — one might think it permissible for his priestly relative to make a bald spot for him, therefore the Torah teaches us [it is not permitted]. And if we were only informed about priests, one might think that because the priest serves our God, certainly after his death he enters the eternal light of life, therefore it is not appropriate to grieve over his death, because it is for his benefit. But for an ordinary Israelite, who is not assured that he will not see the face of Gehenna, one might think it is permissible to grieve for him and make a bald spot on his account, therefore the Torah teaches us [it is not permitted].

לא יקרחו, even though I have permitted the priests to defile themselves to bury their close relatives and express mourning rites, I have not permitted them to exaggerate such displays of mourning to include the making of bald spots on their heads and to make incisions in their flesh. As our sages phrased it, “just as the previous verses dealt with the dead, so the verses in front of us deal with honour for the dead.”(Torat Kohanim 1,3)

ופאת זקנם לא יגלחו NEITHER SHALL THEY RAZE THE CORNER OF THEIR BEARD — Because it is written in the prohibition addressed to the ordinary Israelites, (Leviticus 19:27) “thou shalt not destroy (תשחית) [the corners of thy beard]”, I might think if one took it (the hair) off with a מלקט or a רהיטני, tweezers or plane-like or file-like tools that may be used for destroying the hair, he is guilty of violating the law! Scripture therefore states here "they shall not raze off (לא יגלחו) the corner of their beard", the two statements supplementing each other, thus teaching that one is liable only for the use of an instrument the employment of which is termed גילוח (razing), and ,which at the same time, involves the destruction of the hair, and this results only from the use of a razor (Makkot 21a).