Parah 12:4-5

Parah 12:4

Let’s say that someone sprinkled the sanctification water from a public window and a person who was sprinkled on entered the Temple. If the water is found to be invalid, he is exempt. If the sprinkling was done from a private window and someone sprinkled on entered the Temple, after which the water was found to be invalid, he is liable. The Kohein Gadol is exempt regardless of whether he was sprinkled on from a private or a public window because the Kohein Gadol is never liable for entering the Temple. People used to slip in front of a certain public window (because of all the water spilled there) but people still walked there and didn’t hesitate to enter the Temple because the Sages have said that used sanctification water doesn’t convey ritual impurity.

Parah 12:5

A ritually-clean person may hold a ritually-unclean axe in his hem and sprinkle it. Even if there’s enough water on the axe for sprinkling, he remains clean. “Enough water for sprinkling” is enough to dip the tops of the stalks and to sprinkle with them. Rabbi Yehuda said that we act as if the hyssop were made of brass (i.e., non-absorbent).