They shall not make baldness upon their head, neither shall they shave off the corner of their beard, nor make any cuttings in their flesh.

Wesley's Notes

21:5 They shall not make baldness - In funerals, as the Heathens did. Though I allow them to defile themselves for some of the dead, yet in no case shall they use these superstitious rites, which also the people were forbidden to do; but the priests in a more peculiar manner, because they are by word and example to teach the people their duty.

Jamieson-Fausset-Brown Bible Commentary

5. They shall not make baldness upon their heads . nor . cuttings in their flesh-The superstitious marks of sorrow, as well as the violent excesses in which the heathen indulged at the death of their friends, were forbidden by a general law to the Hebrew people (Le 19:28). But the priests were to be laid under a special injunction, not only that they might exhibit examples of piety in the moderation of their grief, but also by the restraint of their passions, be the better qualified to administer the consolations of religion to others, and show, by their faith in a blessed resurrection, the reasons for sorrowing not as those who have no hope.

Matthew Henry's Concise Commentary

21:1-24 Laws concerning the priests. - As these priests were types of Christ, so all ministers must be followers of him, that their example may teach others to imitate the Saviour. Without blemish, and separate from sinners, He executed his priestly office on earth. What manner of persons then should his ministers be! But all are, if Christians, spiritual priests; the minister especially is called to set a good example, that the people may follow it. Our bodily infirmities, blessed be God, cannot now shut us out from his service, from these privileges, or from his heavenly glory. Many a healthful, beautiful soul is lodged in a feeble, deformed body. And those who may not be suited for the work of the ministry, may serve God with comfort in other duties in his church.