A bed of which half was stolen, or half was lost, or which was divided by brothers, or [divided by] partners, is tahor. If they put it back together, it is susceptible to tumah from now on. [The components of] a bed can contract tumah as a unit, and [they] can be purified as a unit, [these are] the words of R’ Eliezer. But the Sages say: [They] can contract tumah [only as individual] parts, and can be purified [only as individual] parts.