The following is from Tractate Shabbat in the Jerusalem Talmud:
9:3
[A] “How do we know of her
who emits semen on the third day [after having had sexual relations] that she
is unclean?
[B] “Since it says, ‘And be
ready against the third day, come not near a woman’ (Ex. 19:15).
[C] “How do we know that
they bathe a child on the third day after circumcision, even if this coincides
with the Sabbath?
[D] “Since it says, ‘And it
came to pass on the third day when they were sore’ (Gen. 34:25).
[E] “How do we know that
they tie a red thread on the head of the scapegoat [which is sent forth]?
[F] “Since it says, ‘Though
your sins be as scarlet, they shall be white as snow’ (Is. 1:18).”
[I:1 A] Said
R. Yohanan, “It was from the procedure at Sinai that they derived the rule [at
M. 9:3A; alternatively, the rule in M. Miq. 8:3]. Moses came down on Tuesday [:
“on the third (of the month)], saying to them, ‘Be ready against the third day,
do not come near a woman’ (Ex. 19:15). Now whoever ceased to have sexual
relations on the third day then may count Tuesday night, Wednesday, Wednesday
night, Thursday, and as to Thursday night and Friday, if a woman emitted semen
on Thursday night [= five spans], she is unclean, but if it was on Friday, she
is clean [after five spans]. [In this case there are five spans of cleanness.]
[B] “As to whoever ceased
to have sexual relations on Wednesday, we may then count Wednesday, Wednesday
night, Thursday, and as to Thursday night and Friday, if a woman emitted semen
at night on Thursday night, she would be unclean, while if it was on Friday by
day, she is clean. [In this case there are fewer than five spans of cleanness,
but it was acceptable.]”
[C] Said R. Yohanan, “This
is the arrangement at Sinai. But for future generations, [there will be either]
four or six [spans of cleanness].”
[D] R. Aqiba says, “There
must always be five such spans, even in the generations to come.” [This is now
amplified.]
[E] There
we have learned: “She who discharges
semen on the third day after having intercourse is clean, the words of R.
Eleazar b. Azariah. R. Ishmael says, “Sometimes there are four spans [after
which the semen loses its efficacy], sometimes five, sometimes six.” [Ishmael
wants two spans, a complete night and the day following it, to elapse to render
the discharge clean. If inter course took place at the end of the first day,
and the discharge at the beginning of the fourth, two complete days or four
spans intervening, it is clean. But if intercourse took place in the morning of
the first day, the discharge will not be clean until the beginning of the
fourth day, a lapse of five spans. So too if intercourse took place in the
evening preceding the first day, the discharge will be clean at the beginning
of the fourth day, that is, six such spans.] R. Aqiba says, “They are always
five spans” [M. Miq. 8:3J–L].
[F] If part
of the first span had passed, they reckon that part of the sixth span completes
it [T. Miq. 6:6D].
[G] Lo, R. Ishmael treats a day as a span and
a night as a span. R. Aqiba treats a day as a span and a night as a span. Then what is at issue between them?
[H] It is whether spans serve to complete
[the necessary period]. R. Ishmael treats part of a span as the whole of it,
and R. Aqiba does not treat part of a span as the whole of it.
[I] It
has been taught contrary to the view of R. Aqiba: Therefore if part of the first season has passed, they reckon that part
of the sixth season completes it [T. Mid. 6:6D].
[J] It
has been taught: R. Eleazar b. Azariah says, “A day and a night constitute
a span, and part of a span is equivalent to the whole of it.”
[K] And
thus has it been taught contrary to the view of R. Eleazar b. Azariah,
“There are occasions in which there is a day and any small amount of time in
addition, and yet [a woman] is clean. There may be two days lacking a [small]
amount of time, and the woman will be unclean.” [Hence part of a span is not
equivalent to the whole of it.]
[L] “A day and any small amount of time in
addition, and she will be clean”: What
would be a practical illustration of such a case?
[M] If the woman had sexual relations on the
eve of the Sabbath prior to sunset, and she emitted semen at the end of the
Sabbath after sunset, lo, we have a full day and just a bit more time, and yet
she is clean.
[N] “Two days less any amount of time, and
she will be unclean”: What would be a
practical illustration of such a case?
[O] If a woman had sexual relations on the
eve of the Sabbath after sunset, and she emitted semen on Sunday prior to
sunset, lo, we have two days lacking only a small amount of time, and yet she
is unclean.
[P] Said R. Yohanan, “In accord with the
views of all parties, it was in the status of people who had immersed [and
awaited sunset for the purification process to be complete that] the Israelites
received the Torah.”
[Q] That
which you have said applies perfectly well to women, but the men already
had completed the rites of purification, did they not?
[R] What
is the scriptural basis for that view? “[And the Lord said to Moses, ‘Go to
the people and] consecrate them today and tomorrow, and let them wash their
garments’ ” (Ex. 19:10).
[S] Said R. Yohanan, “This represents the
view of R. Eleazar b. Azariah, R. Ishmael, and R. Aqiba. But in the view of
sages, the semen remains valid for three days. From that point onward it
putrefies.”
[T] This
accords with that which R. Zeira said, in the name of R. Yohanan:
“ ‘This is the law for the Zab
and for him who has an emission of semen, becoming unclean thereby’ (Lev.
15:32). Just as the law for the Zab
applies for three days, so the law for the one who emits semen applies for
three days. (Jacob Neusner, The Jerusalem Talmud: A Translation
and Commentary [Peabody, Mass.: Hendrickson Publishers, 2008], Logos Bible Software
edition)