Tosefta zu Schir haSchirim 1:3

[Regarding] anything that is susceptible to become impure with corpse-impurity, even [that which becomes] impure does not possess madaf impurity^*אינו מדך (see MS Vienna and GR"A), and whatever does not have madaf impurity for terumah does not possess madaf impurity for the purification ritual, the words of Rabbi Eliezer. It so happened with Shamaiah,^*tr. from "the words" to "Shamaiah" follows MS Vienna and GR"A a man from Kfar Otney who had in his hand a flask full of waters of purification, and shut a door which had a key that was impure with corpse-impurity attached to it, and he came and asked Rabbi Yochanan ben Zakkai, and he said to him, "Shamaiah, go and sprinkle your waters." And Rabbi Yehoshua says, even what which is pure possesses madaf impurity. And it so happened with Rabbi Yishmael, that he was walking after Rabbi Yehoshua, and he said to him, "One who is pure for the purification ritual, who moves a key that is pure for terumah -- what is he, impure or pure?" He said to him, "Why [would he be impure]?" He said to him, "Lest it possess old impurity^*i.e., impurity retained by metal vessels after they are recast (see Shab. 16b:2), or lest he forgot and moved something impure." [Rabbi Yehoshua then] diverted him to another topic. He said to him, "Yishmael, my brother, how do you read [the verse] 'your love is more delightful than wine'^*i.e., should the word "your" be read masculine or feminine (Songs 1:2)?" He said to him "Your (fem.) love is more delightful than wine." He said to him, "That is not so. For behold, its companion-verse (Songs 1:3) is instructive thereon: 'The fragrance of your (masc.) ointments is sweet.'" And the Sages say, that which is impure possesses madaf-impurity, and that which is pure does not possess madaf-impurity. For the impurity that they spoke about was corpse-impurity and not madaf-impurity. Rebbi says, one who is pure for the purification [ritual] who [indirectly] moves the spit or the urine of one who is pure for terumah is impure. One who [indirectly] moves his blood, behold, that one is pure. One who [indirectly] moves a sheretz or a carcass or a seminal emission, Rabbi Eliezer renders him pure, and Rabbi Yehoshua renders him impure.