Mishnah Parah 12:4: One who sprinkles [onto another individual] from a public window, and he [the sprinkled individual, assuming he has been purified,] enters the temple, and [subsequently] the waters [he was sprinkled with] are found to have been invalid, he is exempt. [One who sprinkles] from a private window, and [the sprinkled individual then] enters the temple, and [subsequently] the waters are found to have been invalid, he is liable. But a high priest, whether [he was sprinkled with waters] from a private window or from a public window, he is exempt, for the high priest is not liable for entering the temple [impure]. They used to slip [on the left over chatat waters spilled] in front of the public window, and they would trample it, but they did not refrain [from doing so, and from entering the temple afterwards], for they said: Chatat waters that have done their mitzva do not cause impurity.

הַמַּזֶּה מֵחַלּוֹן שֶׁל רַבִּים וְנִכְנַס לַמִּקְדָּשׁ וְנִמְצְאוּ הַמַּיִם פְּסוּלִים, פָּטוּר. מֵחַלּוֹן שֶׁל יָחִיד וְנִכְנַס לַמִּקְדָּשׁ וְנִמְצְאוּ הַמַּיִם פְּסוּלִין, חַיָּב. אֲבָל כֹּהֵן גָּדוֹל, בֵּין מֵחַלּוֹן שֶׁל יָחִיד בֵּין מֵחַלּוֹן שֶׁל רַבִּים, פָּטוּר, שֶׁאֵין כֹּהֵן גָּדוֹל חַיָּב עַל בִּיאַת הַמִּקְדָּשׁ. מַחֲלִיקִין הָיוּ לִפְנֵי חַלּוֹן שֶׁל רַבִּים וְדוֹרְסִין וְלֹא נִמְנָעִין, מִפְּנֵי שֶׁאָמְרוּ, מֵי חַטָּאת שֶׁעָשׂוּ מִצְוָתָן, אֵינָן מְטַמְּאִין:

Mishnah Parah 12:5: One who is pure can grasp an impure axe in a fold of his clothing and have one sprinkle onto it. Even if [after the sprinkling] it has on it a [sufficient] amount of water for sprinkling, he is pure. [Generally carrying chatat waters renders one impure, but in this case the waters have already done their mitzva, as noted in the previous Mishna.] And how much must the waters be in order to be an amount for sprinkling? [Enough] that one may dip the tips of the stalks and sprinkle. Rabbi Yehuda says: We view them as if they were on a hyssop of copper [i.e. we also take into account water which has been absorbed and is no longer visible, since copper does not absorb].

אוֹחֵז הוּא הַטָּהוֹר בַּקַּרְדֹּם הַטָּמֵא בִּכְנָפוֹ, וּמַזֶּה עָלָיו. אַף עַל פִּי שֶׁיֵּשׁ עָלָיו כְּדֵי הַזָּיָה, טָהוֹר. כַּמָּה יְהֵא בַמַּיִם וְיִהְיֶה בָהֶם כְּדֵי הַזָּיָה. כְּדֵי שֶׁיַּטְבִּיל רָאשֵׁי גִבְעוֹלִין וְיַזֶּה. רַבִּי יְהוּדָה אוֹמֵר, רוֹאִים אוֹתָם כְּאִלּוּ הֵן עַל אֵזוֹב שֶׁל נְחשֶׁת: