Reference for Menachot 80:11

מתקיף לה רב פפא ממאי דגברא לאוסופי קא מיכוין דלמא לבטולי קא מיכוין ובל תוסיף ליכא מעשה איכא

it is valid!<span class="x" onmousemove="('comment',' I.e., the second set of fringes satisfy the law, although when these fringes were inserted there was no obligation for them, since the first set of fringes had not yet been removed.');">¹⁶</span> - Raba replied, Since one thereby transgresses the law of Thou shalt not add thereto,<span class="x" onmousemove="('comment',' Deut. XIII, 1. At the time when each fringe of the second set is inserted there is a transgression of this precept, so that the fringe so made is null and void, and therefore only when the first set is removed does the second set of fringes come into existence, Where, however, the fringes were inserted in a three-cornered garment, this act, not being an infringement of the law, is an act of consequence, and when a fourth corner is added and a fringe attached thereto, the first three fringes are disqualified as being ready made.');">¹⁷</span>

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