Mishnayos Keilim Perek 28 Mishnah 2

[A piece of cloth] less than three [handbreadths] square that was adapted for the purpose of stopping up a hole in a bath house, of emptying a cooking-pot or of wiping with it the mill stones, whether it was or was not kept in readiness for any such use, is susceptible to uncleanness, the words of Rabbi Eliezer. Rabbi Joshua says: whether it was or was not kept in readiness it is pure. Rabbi Akiba ruled: if it was kept in readiness it is susceptible, and if it was not kept in readiness it is pure.