Musar su Geremia 30:17

On the absence of this, the prophets complained saying: "And He saw that there was no man, and He was astounded for there was no intercessor"(Yeshaya 59:16) and "I looked, and there was none to help; and I was astonished that there was no one to uphold" (Yeshaya 63:5). And it is stated: "it is Zion; no one inquires after her" (Yirmiyahu 30:17), which our sages expounded: "this implies it needs inquiring after" (Sukkah 41a).

ולא תשחית את פאת זקנך...לא תקיפו פאת ראשכם . The reason for this string of prohibitions concerning the defacing of the head or the skin is to make a clear distinction between our mode of living and that of the pagan priests. A G–d-fearing person does not use the razor anywhere near his throat so that he may not accidentally injure his skin close to where his sideburns grow. The use of scissors in all those areas is permitted. Since we have the principle that the commission of one sin usually triggers the commission of other sins, the Torah prohibits using the razor on "the corner of your head,” so that, having failed to observe this injunction you should not also become guilty of using it on the "corners of your beard."