Keilim24: 5
שְׁלֹשָׁה תַרְבּוּסִין הֵן: שֶׁל סַפָּרִין — טָמֵא מִדְרָס. שֶׁאוֹכְלִין עָלָיו — טָמֵא טְמֵא מֵת. וְשֶׁל זֵיתִים — טָהוֹר מִכְּלוּם.
There are three tarbusin: [The tarbus] of a bloodletter [is susceptible to becoming] tamei with midras [tumah]. [A tarbus] on which people eat [is susceptible to becoming] tamei with corpse-tumah. And [a tarbus] of olives is tahor from any [form of tumah].