Mishnah Niddah 9:6: Seven compounds remove a [blood] stain [and can thereby be used to test whether a stain is blood]: bland saliva, bean water, urine, lye, soap, cimolite [a type of clay used for cleaning], and potash [a potassium compound used for soap]. If one immersed it [a stained item] and prepared pure items upon it, and passed these seven compounds over it and the stain did not pass, it is thereby dye, the pure items remain pure, and one does not need to immerse it. If it did pass, or if it faded, it is thereby a [blood] stain, and the pure items are impure, and one must immerse it.

שִׁבְעָה סַמָּנִין מַעֲבִירִין עַל הַכֶּתֶם. רֹק תָּפֵל, וּמֵי גְרִיסִין, וּמֵי רַגְלַיִם, וְנֶתֶר, וּבוֹרִית, קְמוּנְיָא, וְאֶשְׁלָג. הִטְבִּילוֹ וְעָשָׂה עַל גַּבָּיו טָהֳרוֹת, הֶעֱבִיר עָלָיו שִׁבְעָה סַמָּנִין וְלֹא עָבַר, הֲרֵי זֶה צֶבַע, הַטָּהֳרוֹת טְהוֹרוֹת, וְאֵינוֹ צָרִיךְ לְהַטְבִּיל. עָבַר אוֹ שֶׁדֵּהָה, הֲרֵי זֶה כֶתֶם, וְהַטָּהֳרוֹת טְמֵאוֹת, וְצָרִיךְ לְהַטְבִּיל:

Mishnah Niddah 9:7: What is bland saliva? That which [is from someone who] has not tasted anything [that day]. Bean water? Ground up grits of beans that had split apart [in water]. Urine? That which has soured. And one must scrub it three times for each and every one. If one passed these [compounds over the stain] out of order [i.e. not in the order in which they appear in the Mishna], or if one passed all seven of them over it at once, [it is as though] he has done nothing.

אֵיזֶהוּ רֹק תָּפֵל, כֹּל שֶׁלֹּא טָעַם כְּלוּם. מֵי גְרִיסִין, לְעִסַּת גְּרִיסִין שֶׁל פּוֹל, חֲלוּקַת נָפֶשׁ. מֵי רַגְלַיִם, שֶׁהֶחֱמִיצוּ. וְצָרִיךְ לְכַסְכֵּס שָׁלשׁ פְּעָמִים לְכָל אֶחָד וְאֶחָד. הֶעֶבִירָן שֶׁלֹּא כְסִדְרָן, אוֹ שֶׁהֶעֱבִיר שִׁבְעָה סַמָּנִין כְּאַחַת, לֹא עָשָׂה וְלֹא כְלוּם: