Comentário sobre Pará 12:4

המזה מחלון של רבים – that stands in the window in the public domain and sprinkles there on the impure that pass by, and he sprinkled on an impure person thinking that the waters that are in his hands are pure for sprinkling.

Introduction This mishnah refers to a window from which they would sprinkle the hatat waters on impure people.

ונמצאו פסולים – if he entered with this sprinkling to the Sanctuary, the impure person is example from a sacrifice [on his entering into the Sanctuary while impure], for this is a doubtful/uncertainty with regard to ritual impurity in the public domain (i.e., by Torah law, if uncertainty arises concerning the ritual purity of a person or an object, and that person or object is in a public domain, they are ritually pure. If the situation arises in a private domain, they are considered ritually impure) and his doubtful purity is deemed to be pure. And Maimonides explained the reason, that this impure person is under compulsion/unavoidably prevented, for he did not have in mind to check if the waters were fit/suitable for sprinkling or not, since he was standing in the public domain and sprinkling on many people. But if he stands in the window of a single individual and sprinkles, the impure person would have to check on the waters if they are fit/suitable, or not, and since he did not check, it is an inadvertent error but not something unavoidably preventable, and if he entered into the Sanctuary with this sprinkling, he is liable for a sacrifice, for this is like a doubtful impurity in the private domain where this doubt is impure.

If one was sprinkling from a window in a public domain and [a man who was thus sprinkled upon] entered the sanctuary, and the water was found to be invalid, he is exempt; A person was sprinkled upon (with hatat waters, of course) from a window in the public domain. He then entered the Temple, assuming that he was pure. It later turns out that the water used to sprinkle upon him was impure. Nevertheless, the person is exempt from bringing a sacrifice to atone for entering the sanctuary while impure. The reason is that since this water was used to purify the public, there would be no reason he should have suspected that it was invalid. This is not an accidental sin (in Hebrew, shogeg). Rather it is something even less, called in Hebrew "anoos" which means he wasn't even negligent. Something totally anticipated happened. We can see from here that if something is being done by many people, one can assume that it is being done correctly.

שאין כהן גדול חייב על ביאת המקדש – as it is written (Numbers 19:20): “[If anyone who has become impure fails to purify himself, [that person shall be cut off from the congregation, [for he has defiled the LORD’s sanctuary],” the waters of purification are equivalent to the congregation, that is to individuals, excluding the High Priest, whose sin is not equivalent to that of individuals.

But if the sprinkling was done from a private window and [a man who was thus sprinkled upon] entered the sanctuary, and the water was found to be invalid, he is liable. However, if the sprinkling was done from a private window, he should have checked to make sure that the water was valid. Since he did not, he is liable for having gone into the sanctuary while impure. He will have to bring a sacrifice to atone for his sin.

מחליקין היו (they would slip [on water]) – meaning to say, that there were so much waters of purification there until people would slip upon them, and even so they would trample on them, because they would not defile, since their Mitzvah was done.

A high priest, however, is exempt, whether the sprinkling upon him was done from a private window or from one in a public domain, for a high priest is never liable for entering the sanctuary. A high priest is never liable for entering the Temple while impure (see Horayot 3:7).

[The people] used to slip before a certain window in a public domain, and [nevertheless] they trod [on that spot] and did not refrain [from entering the sanctuary], because they said that hatat waters whose mitzvah had been performed do not defile. The mishnah describes a puddle that formed underneath the window from which they would sprinkle upon people who wanted to enter the Temple. The floor got so wet that people would slip on it (Jerusalem can be slippery!). Nevertheless, people didn't refrain from stepping in this water, because they knew that once hatat waters have been used to perform their mitzvah, the purification, they no longer convey impurity. As an aside, this is one of the few places, perhaps the only place, in Parah that describes some realistic scene concerning the sprinkling of the hatat waters.