A robe of fine linen - A robe made of בוץ buts, probably the tuft or beard of the Pinna Magna, a species of muscle found every where on the shores of the Mediterranean, growing sometimes, as I have seen, to a foot and a half in length. I have seen a pair of gloves made of this very rich stuff; the color is a deep dark yellow, something inclining to what is called the lilac. The buts or byssus was not heard of in Israel before the time of David: after that it is frequently mentioned.
“Fine linen” (byssus) is here first spoken of as used for dress. It seems to have been reserved for nobles of the highest rank Esther 8:15, for kings, and for priests 2 Chronicles 5:12. David‘s robe was probably worn, like that of the high priest, immediately under the ephod, and may, like that, have reached the feet.