וְרֹאשָׁם֙ לֹ֣א יְגַלֵּ֔חוּ וּפֶ֖רַע לֹ֣א יְשַׁלֵּ֑חוּ כָּס֥וֹם יִכְסְמ֖וּ אֶת־רָאשֵׁיהֶֽם׃
Mereka tidak boleh mencukur gundul kepala mereka, dan tidak boleh membiarkan rambut mereka tumbuh panjang; mereka harus memangkas rambut kepala mereka dengan rapi.
Sefer HaChinukh
That the priests not enter the Temple with grown hair: That the priests not enter the Temple with grown hair, like mourners do — meaning to say that they not grow their hair long, as it is stated (Leviticus 10:6), “you shall not let your head be wild.” And the Targum (Aramaic translation of Onkelos) said, “Do not increase locks.” And Yechezkel the prophet elucidated and said (Ezekiel 44:20), “and they shall not send forth locks.” And so too with the metsora (Leviticus 13:45), “and his head shall be wild” — and they said in Sifra [that it means], “He grows locks.”
Shulchan Arukh, Yoreh De'ah
A mourner is forbidden to cut his hair,1M.K. 14a, b, derived from the Biblical injunction, ‘Let not the hair of your heads go loose’ (Lev. X, 6), whence we infer that for everyone else cutting the hair is forbidden. Cf. Ez. XLIV, 20. If a mourner is invited to be the Sandek at a circumcision, or if he is the Mohel, he is forbidden to cut his hair and this does not come within the ruling mentioned infra § 391, 2 Gloss on the authority of MaHaRIL — P.Tesh. both the hair of his head as well as the hair of his beard, or any hair that he has [on his body], even that of the secret parts, — for the entire thirty days.2Sem(H). VII, 1 also ibid. p. 230. Cf. Asheri to M.K. 23a; Yeb. 43a, Tosaf. s.v. במקום. [As to] the hair of the upper lip and that which [droops] on the sides,3M.K. 18a in accord with Samuel. — [the law is that] whatsoever causes a hindrance in partaking of food,4Ibid. in accord with R. Ammi. is forbidden [to be trimmed] during the seven [days of mourning] and permitted after the seven [days of mourning].5Tur on the authority of Ghayyat and Hal. Ged. M.K. ibid., Tosaf. s.v. ובגנוסטרי. In B.Yos. Caro states that this was permitted only on Ḥol ha-Moed in accord with Yad, Ebel V, 2 and RaBaD, but not with respect to mourning. Kes. Mish. ibid. Sem(H) ibid. is adduced that trimming the upper lip and the drooping sides was permitted only with respect to Ḥol ha-Moed, but not regarding mourning. N in T.H. cites Y.M.K. III, 1(82a) according to which even during the seven days of mourning this would be permitted. Caro (in B.Yos.) also quotes Y. ibid., but makes a compromise and rules in accord with Ghayyat. W.G. states that the ruling of N in T.H. is fundamental.