Introduction This mishnah contains additional testimony of Rabbi Zadok concerning the validity of water for use in a mikveh. In the introduction to the previous mishnah we mentioned that flowing water such as a stream need not contain 40 seahs in any one place in order to be valid to be used as a mikveh. However, if the flowing water is directed by vessels, then it must contain 40 seahs in one place to be used as a mikveh.
Rabbi Zadok testified concerning flowing water which was made to run in a stream through nut-leaves, that it was valid. In the scenario under discussion a person has used nut-leaves to direct a stream of water. The question is, are these nut-leaves to be considered like a vessel? If they are then the stream would require 40 seahs in one place in order to be used as a mikveh. Rabbi Zadok testifies that these nut-leaves are not to be considered like vessels, even though the person who set them up may have used them in a similar fashion. Therefore the stream is valid as a mikveh even without 40 seahs in one place.
There was such a case at Ahaliyya, and when the case came before [the Sages in] the Chamber of Hewn Stone they declared it valid. This section brings additional support for Rabbi Zadok’s testimony. A case such as this actually happened in a place called Ahaliyya, and the Sages who sat in the Chamber of Hewn Stone, which was located in the Temple in Jerusalem (Sanhedrin 11:2) ruled that the water was valid without 40 seahs. Note the similar structure between this mishnah and the previous mishnah.