Reference for Shabbat 223:4
ורצועות מנעל וסנדל: איתמר התיר רצועות מנעל וסנדל תני חדא חייב חטאת ותניא אידך פטור אבל אסור ותניא אידך מותר לכתחילה קשיא מנעל אמנעל קשיא סנדל אסנדל
AND THE LACES OF HER SHOES OR SANDALS. It was stated: If one unties the laces of his shoes or sandals, — one [Baraitha] taught: He is liable to a sin-offering; another taught: He is not liable, yet it is forbidden; while a third taught: It is permitted in the first place. Thus [the rulings on] shoes are contradictory, and [those on] sandals are contradictory? [The rulings on] shoes are not contradictory: when it teaches, 'he is liable to a sin-offering', it refers to cobblers' [knots];<span class="x" onmousemove="('comment',' Rashi: when the cobbler inserts the lace in the shoe, he ties it there permanently. — Perhaps the shoes and its laces were so arranged that part of the lace was permanently fastened. ');"><sup>7</sup></span> 'he is not liable, but it is forbidden' — that refers to [a knot] of the Rabbis;<span class="x" onmousemove="('comment',' Sometimes they tied it very loosely, so that the shoe could be removed and put on without untying. Thus whilst not actually permanent to involve a sin-offering, it is semi-permanent, hence forbidden. ');"><sup>8</sup></span> 'it is permitted in the first place', refers to [the knots] of the townspeople of Mahoza.<span class="x" onmousemove="('comment',' Who were particular that all their garments should fit exactly. Hence their shoes too were tightly fastened and had to be untied every time they were put on or off. perhaps they are mentioned in particular because being well-to-do they thought more of dress; cf. Obermeyer, p. 173. ');"><sup>9</sup></span>