Mishnah Taharos 4:6: If there are two spittles, one which is impure [like any found spittle, as seen in the previous Mishna] and the other pure [where it is known to have come from a pure person], we suspend [and neither burn nor eat the terumah] for their touching, being carried, or being moved in a private domain [when there is this uncertainty as to whether it was the impure spittle or the pure]; and [the same rule applies also in cases of uncertainty regarding] their touching in a public domain when they are moist, and for their being carried when they are either moist or dry. If there was just one spittle and someone touched it, carried it, or moved it in the public domain, terumah [which he then came into contact with] is burnt on his account, and certainly if this happened in a private domain [it is also burnt].

שְׁנֵי רֻקִּין, אֶחָד טָמֵא וְאֶחָד טָהוֹר, תּוֹלִין עַל מַגָּעָן וְעַל מַשָּׂאָן וְעַל הֶסֵּטָן בִּרְשׁוּת הַיָּחִיד, וְעַל מַגָּעָן בִּרְשׁוּת הָרַבִּים בִּזְמַן שֶׁהֵן לַחִין, וְעַל מַשָּׂאָן בֵּין לַחִין וּבֵין יְבֵשִׁין. הָיָה רֹק יְחִידִי וְנָגַע בּוֹ וּנְשָׂאוֹ וְהִסִּיטוֹ בִּרְשׁוּת הָרַבִּים, שׂוֹרְפִין עָלָיו אֶת הַתְּרוּמָה, וְאֵין צָרִיךְ לוֹמַר בִּרְשׁוּת הַיָּחִיד:

Mishnah Taharos 4:7: The following uncertainties [regarding impurity status] were declared pure by the Sages: the uncertainty of drawn waters for a mikvah [a pool for ritual immersion which must contain natural, undrawn water; the uncertainty is a case in which it is uncertain whether a mikvah contains enough drawn water to invalidate it from being able to purify those that immerse it in]; the uncertainty of an impurity floating on the water's surface; the uncertainty of liquids regarding whether they themselves have become impure--such [liquids] are impure, and [the uncertainty] regarding whether they rendered [something else] impure--such [items] are pure; the uncertainty of hands regarding whether they themselves have become impure, or have rendered [something] impure, or have themselves become pure, [in all three cases] they are pure; the uncertainty of the public domain [i.e. an uncertainty regarding purity status which was generated when something was in the public domain]; the uncertainty regarding [the purity status of something that came into contact with something that is impure only according to] the words of the Scholars; the uncertainty [regarding the purity status] of non-sanctified foods; the uncertainty regarding [the purity status of something which may have been rendered impure by] vermin; the uncertainty of blights [i.e. regarding the purity status of someone or something that may have been rendered impure by someone impure due to an illness, such as leprosy]; the uncertainty regarding [one's] status as a Nazirite[i.e. like someone who took a vow to be a Nazirite contingent on something which remains uncertain]; the uncertainty regarding [the status of] a first born; and the uncertainty regarding [one's obligation to bring] sacrifices.

אֵלּוּ סְפֵקוֹת שֶׁטִּהֲרוּ חֲכָמִים. סְפֵק מַיִם שְׁאוּבִים לַמִּקְוֶה. סְפֵק טֻמְאָה צָפָה עַל פְּנֵי הַמָּיִם. סְפֵק מַשְׁקִין, לִטָּמֵא, טָמֵא, וּלְטַמֵּא, טָהוֹר. סְפֵק יָדַיִם, לִטָּמֵא וּלְטַמֵּא וְלִטַּהֵר, טָהוֹר. סְפֵק רְשׁוּת הָרַבִּים. סְפֵק דִּבְרֵי סוֹפְרִים. סְפֵק הַחֻלִּין. סְפֵק שְׁרָצִים. סְפֵק נְגָעִים. סְפֵק נְזִירוּת. סְפֵק בְּכוֹרוֹת. וּסְפֵק קָרְבָּנוֹת: