Mishnayos Keilim Perek 20 Mishnah 6

סדין שהוא טמא מדרס – and it is appropriate to be defiled through treading, as it states, but it is not actually defiled through treading. For if so, as it is taught in the concluding section ‘of the Mishnah] “that is susceptible to uncleanness from corpse uncleanness,” let it be taught “but it is impure through contact with treading, as it is taught in the third chapter of Tractate Menahot (הקומץ רבה) [see also Tosefta Tractate Kelim Bava Metzia, Chapter 11, Halakha 9].

ועשאו וילון – a curtain for the opening, or a curtain for a ship. And specifically, when he made it through a change in action, but thought [alone] does not remove it from defilement that it was appropriate for it.

אבל טמא טמא מת – because the sun warms it (see Talmud Betzah 14a) it (i.e., the sheet) is wrapped in its rims periodically, therefore, it is not annulled from the laws of a vessel.

מאימתי טהרתו – that the law of treading is annulled from it.

משיתפר – In the Tosefta it is proven that the School of Shammai (see above, Tractate Kelim Bava Metzia 11:6) requires when it is torn and one fixes it to the measure of the opening, and one sews on it loops/couplings to hang it on a curtain or on a ship. But the School of Hillel states: “when he ties it up” and it doesn’t require tearing. But rather, one he ties on it the loops/couplings in order to suspend them upon them. And there are books that have the reading: “The School of Shammai states from when it is broken,” and that this is the reading, meaning to say, that when he breaks it and tears it in order to sew it to the measure of the opening.

ר' עקיבא אומר משיקבע – from the time that he will hang it on the opening or on the ship. And the Halakha is according to the School of Hillel.