Shabbat 157b — the Talmud in English

Rabbi Yehuda said in the name of Rav: There was a small

path

that

was there,

between two houses. And there was impurity

there, on this path.

And a cracked vat was placed upon the roofs

of the two houses. And the corpse was lying beneath the place of the crack. However, it was not known whether the crack had the measure of a tefach, or not. And in the wall of the houses facing the path there was a window.

And it is established for us: If the corpse is lying in a shelter, in such a manner that the impurity has no place to exit upward, it spreads into the houses beside the shelter, through the hole in the wall [if the hole has the measure of the fullness of a fist]. And so it was in that incident. For the vat sheltered over the corpse and prevented its impurity from exiting upward. Therefore, the impurity was to enter the houses on the sides of the path through the opening [the window] in the wall, and render everything within them impure with the impurity of a shelter.

And

in order to prevent this, before the soul of the corpse departed,

they stopped up the opening

[the window in the wall]

with a tefiah

[an earthenware jug], with its back toward the path where the corpse was. Since an earthenware vessel does not become impure through its back, its back forms a barrier against the impurity.

And after he died, they wanted to remove the tefiah from the window. But they feared that by doing so they would bring impurity into the house again. Therefore, they had to measure the size of the crack in the vat. For if the crack had the measure of a tefach, and the corpse was lying opposite it, the impurity would not spread to the sides. Rather, it would exit above, through that opening. But if the crack were less than an opening of a tefach, the impurity would not exit there. And if the stopper of the window were removed, the impurity would enter the house.

Therefore, they took the measuring vessel [an earthenware vessel] that had exactly the measure of one tefach by one tefach.

And they tied

it,

the measuring vessel,

to a long stick,

with a reed.

And they raised it opposite the crack, to see whether it entered into it. And through this it was possible

to know whether there was there

in the crack that

in the vat

the measure

of an opening of a tefach,

and the impurity could exit through it and would not enter the house,

or not.

And they specifically tied it with a reed, because it is fit for animal food, and it does not become nullified to the vessel so as to be tied to it with a permanent knot. For in the end it will be removed for the animal’s eating.

Alternatively, it is not a permanent knot, because when it dries, it becomes detached by itself. Rashi, according to the Rashash.

We learned in the Mishna:

“And from their words we learned that one may stop up, measure, and tie on Shabbat.”

Ulla happened to come to the house of the Exilarch. He saw Rabba bar Rav Huna sitting in a

vat

of water, and measuring

it

for him

for the size of the vat.

He said to him: Say:

This

that the Sages say “one may measure on Shabbat,” they said this only with regard to

measuring for a

mitzva.

For example, for the laws of impurity, or for the fitness of a ritual bath. But with measuring

that

is

not

for a

mitzva, who said

that it is permitted?

He said to him:

Rabba bar Rav Huna: I have no need whatsoever for this measurement.

I am merely engaging in it.

And they prohibited only measuring in which he has a need.

We have returned to you, chapter “One Whom Darkness Overtook.”

And the tractate Shabbat is concluded.