Rashi on Leviticus 19:19/רש"י על ויקרא י״ט:י״ט

1חקתי תשמרו ‎את YE SHALL KEEP MY ORDINANCES — These are they: “Thou shalt not cause two kinds of thy cattle to gender etc.”, (and the other ordinances laid down in this verse), for by the term חוקים are meant those enactments of the King for which no reason is given and those that precede are not of this character.

2ובגד כלאים NEITHER SHALL A GARMENT MINGLED OF LINEN AND WOOLLEN [COME UPON THEE] — Why is this st‎atement made (how does the particular form of words used here tell us some point of law which is not contained in Deuteronomy 22:21 which bears upon the same subject)? Because Scripture states there “Thou shalt not wear שעטנז, wool and linen together” I might think that one must not wear in combination wool (i. e. wool as it comes from the shearing) and combed flax! Scripture therefore states here “a garment (i. e. something made of a cloth) [mingled of woollen and linen shall not come upon thee]”, thus excluding loose pieces of wool and flax in combination, which do not form a בגד. Whence do we know that this prohibition extends to felt-stuff (which though not being really בגד, since the material is not worked up into cloth, is, however, made of wool and linen pressed into one material)? Because Scripture states in Deuteronomy “שעטנז shall not come upon thee” which means a material that is calendered (pressed, שוע), or woven (טוי) or twisted (נוז) together — (שעטנז is taken to be an abbreviation of these words) (Sifra, Kedoshim, Chapter 4 18). I say that נוז is an expression for material which is dried by rubbing between the fingers in order to extend it into threads, these being then twined together so that it forms a coherent web. This is called tistre in O. F. (cf. Rashi on Gittin 59a s. v. דבר הנמלל ונמתח). Similar is the expression to be found in the Talmud (Moed Katan 12b): חזין לגזאי דאית בהון, “The sesame-plant may be plucked on חולו של מועד because it is fit for use on account of the נזאי, the dried-up kernels which it contains” — which word, viz., נזאי, we explain to mean as much as “withering”, flestre in O. F.. Menachem explains שעטנו to denote a combination of wool and linen.