Yevamot 5B

מקרא קמא. אם כן, לימא קרא: ״ציצית תעשה לך״, ״גדילים״ למה לי? שמע מינה לאפנויי.

they learn this from the first verse, which permits a mixture of diverse kinds of wool and linen in tzitzit. As for the previous claim that in the opinion of the Rabbis the phrase “wool and linen” is not superfluous and therefore there is no cause to derive from the juxtaposed verses, the answer is as follows: If so, that no homiletical interpretation can be derived from this source, let the verse say only: You should make fringes for yourself. Why do I need the expression “twisted fringes” (Deuteronomy 22:12)? Conclude from this that this phrase is free, i.e., a homiletical interpretation can be derived by the juxtaposition of verses due to this superfluous phrase.

האי לשיעורא הוא דאתא: גדיל ⁠— ״שנים״, ״גדילים״⁠ — ארבעה: עשה גדיל ופותלהו מתוכו!

The Talmud raises a difficulty: This term, “twisted fringes,” comes to teach the measure of tzitzit, i.e., the requisite number of strings for the fringes, as it is taught: Twisted fringe, in the singular, indicates that it is entwined, which requires at least two strings. Consequently, when the verse says “twisted fringes” in the plural, it is referring to 4 strings. This means that one must prepare a twisted fringe and double it over from the middle, so that there are 8 strings. Consequently, the term “twisted fringes” is not superfluous at all.

אם כן, לימא קרא ״לא תלבש שעטנז״, ״צמר ופשתים יחדו״ למה לי? שמע מינה לאפנויי.

The Talmud responds: If so, that this phrase is not extraneous at all, and therefore it cannot be used as a homiletical interpretation by the juxtaposition of verses, let the verse say merely: You should not wear diverse kinds [sha’atnez]. Why do I need the verse to add the phrase “wool and linen together”? Conclude from this that this phrase is free, and a homiletical interpretation can be derived from the juxtaposition of verses.