[Regarding] a hide that is tamei midras and one decided [to use] it for straps or for sandals, as soon as he applies the knife to it, it is tahor; [these are] the words of R’ Yehudah. But the Sages say: Until he reduces it [to] less than five handbreadths. R’ Elazar the son of R’ Tzadok says: Even if one makes a napkin from a hide, it remains tamei, but from a mattress, it is tahor.