Adam Clarke on Daniel 3:21

Their hats - This word, hat, is found only in this place in the Old Testament. The word סרבל sarbal properly means an outer garment. Herodotus, who lived about one hundred years after Daniel, says, "the dress of the Babylonians consisted of a tunic of linen reaching down to the feet; over this a tunic of woollen; and over all a white short cloak or mantle, χλανιδιον; and on their heads they wore turbans, μιτρησι." Following this, Mr. Parkhurst translates the verse thus: "Then these three men were bound [בסרבליהון besarbaleyhon] in their Cloaks, [פמישיהון patesheyhon] their Turbans, [וכרבלתהון vecharbelathehon] and in their Upper (woollen) Tunics, [ולבושיהון ulebushehon] and their Under (linen) Tunics." And as, according to this interpretation, their סרבלי sarbaley were their outermost garments, we see the propriety with which it is observed at Dan 3:27 that these were not changed by the fire.