Parah, Chapter 12, Mishnah 2. This chapter is occupied with the ezov, the hyssop that is dipped into the mei chatas, and with the sprinkling itself. Our Mishnah takes up a series of cases in which something went slightly wrong: either we cannot be sure exactly where the drops came from, or we cannot be sure exactly where they landed.
The Mishnah begins: "Hizah, safek min hachut, safek min hakush, safek min hagiv'ol, hazyaso psulah." He sprinkled, but there is a doubt: perhaps the water came off the thread, or off the spindle thread, or off the stalk rather than from the hyssop itself. In such a case the sprinkling is invalid.
The next case: "Hizah al shnei kelim, safek al shnehem hizah, safek mechaveiro mitzalav, hazyaso psulah." He sprinkled toward two vessels, and now he is uncertain: did he actually sprinkle onto both of them, or did the water land on one and drip over from it onto the other? Here too the sprinkling does not count.
A third case of the same type: "Machat shehi netunah al hacheres, vehizah aleha, safek al hamachat hizah, safek min hacheres, hazyaso psulah." There is a needle set into a piece of earthenware. He dips and sprinkles in its direction, and afterward he is not sure whether the drops reached the needle itself or only the earthenware vessel in which it sits. Such a sprinkling is no good.
A flask with a narrow mouth
"Slochis shepiha tzar, tovel umaleh kidarko." If the vessel holding the mei chatas is a flask with a narrow opening, so that the hyssop practically fills the mouth when it goes in, one may nevertheless dip and draw up the water in the ordinary way, and the sprinkling is valid. Rabbi Yehudah disagrees in part: "Rabbi Yehudah omer, hazayah rishonah" - according to him this holds only for the first sprinkling.
The Mishnah continues with a related situation: "Mei chatas shenisma'atu, tovel afilu rashei giv'olin umazeh, uvilvad shelo yisapeg." The mei chatas in the vessel has gone down and there is very little left. He may still dip, even if only the very tips of the stalks reach the water, and sprinkle from them. The one condition is shelo yisapeg: he must not wipe the hyssop off against the mouth of the flask as he pulls it out, since in that way the little water he drew up would be lost.
There is an opinion that when the mouth of the vessel is narrow enough, whatever is wiped off simply falls back inside, so there would be nothing to be concerned about. That, however, is not the way we pasken.
Intent and direction
"Niskaven lehazos lefanav vehizah le'acharav" - he set out to sprinkle in front of himself and the water went behind him; "le'acharav vehizah lefanav" - he intended to sprinkle behind himself and the water went in front. In either case, "hazyaso psulah," the sprinkling is invalid.
Contrast this with "lefanav vehizah al tz'dadim shelefanav, hazyaso ksherah." His aim was forward, and the drops did land forward, only somewhat off to one side. Since nothing left the area he was directing himself toward, the sprinkling holds.
Sprinkling on people and on vessels
The Mishnah then turns to the one receiving the water: "Mazin al ha'adam", and this may be done "mida'ato veshelo mida'ato." The awareness of the person being purified is simply not a condition; the water accomplishes what it accomplishes whether he is attending to it or not.
The Mishnah closes with a point about scope: "Mazin al ha'adam ve'al hakelim", and it adds "va'afilu hen me'ah." One act of sprinkling can serve a human being along with utensils, and their number presents no difficulty: should a hundred items be included in that single motion of the ezov, every one of them is considered to have received the sprinkling.