Reference for Menachot 77:1
דלמא דאיקטר
Perhaps [they said so only where] there were knots [after each joint].<span class="x" onmousemove="('comment',' Where, however, there were no knots after each joint, a curtailed thread would render the whole invalid. Hence there is no proof that there must be a knot after each joint. rae');"><sup>1</sup></span> Raba also said, You can infer from this that the upper knot<span class="x" onmousemove="('comment',' Here Rashi suggests, either the last knot (as above) that is furthest from the garment at the end of all the windings, or (v. Tosaf. s.v.) the first knot that is made as soon as the threads have been inserted in the corner of the garment.');"><sup>2</sup></span> is an ordinance of the Torah;<span class="x" onmousemove="('comment',' I.e., a law given to Moses at Sinai.');"><sup>3</sup></span>