In particular the priests should have linen bonnets upon their heads—literally, linen tires shall be upon their heads—and linen breeches upon their loins. To infer from the use of מִגְבָּעוֹת in Le Ezekiel 8:13 and of פְאֵר here for the head-dress of the priests, that Ezekiel was composed before Leviticus, is not convincing.
Smend explains the latter term as the customary headdress of common people, and the former as a specially ornamental tiara or turban. Gesenius reverses this meaning, making the former the ordinary round cap, and the latter a tiara (see for the former, Exodus 28:40; Exodus 29:9; Exodus 39:28; and for the latter, Exodus 39:28; Isaiah 61:10; Ezekiel 24:17, Ezekiel 24:23).
In addition, the priests should not gird themselves with any thing that causeth sweat; literally, should not gird themselves in, or with sweat, which was another way of forbidding them to wear woollen clothing, which might cause them to sweat and so lead to uncleanness.