Kelim, Chapter Fourteen, Mishnah Five
1) The clean parts of a wagon are the following: the yoke that is only plated [with metal], side-pieces made for ornamentation, tubes that give out a noise, the lead at the side of the necks of the cattle, the rim of the wheel, the plates and mountings, and all other nails, all of these are clean.
2) Metal shoes of cattle are susceptible to impurity but those made of cork are clean.
3) When does a sword become susceptible to impurity? When it has been polished.
a) And a knife? When it has been sharpened.
Section one: This section is the opposite of yesterday’s mishnah. The objects mentioned here are either ornamental or not absolutely necessary for the functioning of the wagon. The yoke that is made of wood but is covered with metal is considered to be a wood vessel and the metal parts serve the wood. Therefore it is clean.
Section two: Metal shoes made so that animals don’t slip are susceptible but not simply because they are shoes. They are susceptible for soldiers, in time of need, use them for drinking. But cork shoes are not used for drinking, and therefore they are not susceptible.
Section three: The mishnah now returns to discuss the topic of when the manufacturing of certain objects is considered to have been completed such that they are susceptible to impurity. A sword is used only after it has been polished, and therefore it is susceptible only then. In contrast, a knife is susceptible as soon as it has been sharpened.