יליף אהל אהל ממשכן כתיב הכא (במדבר יט, יד) זאת התורה אדם כי ימות באהל וכתיב התם (שמות מ, יט) ויפרש את האהל על המשכן מה להלן בידי אדם אף כאן בידי אדם ורבנן אהל אהל ריבה
He derives by means of a verbal analogy that only a man-made tent transmits impurity, deriving the tent written with regard to impurity imparted by a corpse from the tent written with regard to the Tabernacle. It is written here with regard to impurity imparted by a corpse: “This is the teaching when a man dies in a tent” (Numbers 19:14). And it is written there with regard to the Tabernacle: “And he spread the tent over the Tabernacle” (Exodus 40:19). Just as there, with regard to the Tabernacle, the tent was established by a person, so too here, with regard to impurity of a corpse, it is a tent established by a person. And according to the Rabbis, because the passage dealing with impurity imparted by a corpse, i.e., tent tent, is repeated several times, this amplifies and includes any structure that provides shelter, even if it is not a standard tent.
וסבר ר' יהודה כל אהל שאינו עשוי בידי אדם אינו אהל ורמינהו חצירות היו בנויות בירושלים ע"ג הסלע ותחתיהם חלל מפני קבר התהום ומביאין נשים עוברות ויולדות שם ומגדלות בניהם שם לפרה
The Gemara asks: And does Rabbi Yehuda hold that the legal status of any tent that is not established by a person is not that of a tent? The Gemara raises a contradiction from a mishna (Para 3:2): Courtyards were built in Jerusalem atop the rock, and beneath these courtyards there was a space of at least a handbreadth due to the concern lest there is a grave in the depths. In that case, the space served as a barrier preventing the impurity from reaching the courtyards above. And they would bring pregnant women, and they would give birth there in those courtyards. And they would raise their children there and would not leave there with the children until they grew. All this was done so that the children would be untainted by any impurity and would be able to assist in the ritual of the red heifer, whose ashes are used to purify those impure with impurity imparted by a corpse.
ומביאין שוורים ועל גביהן דלתות ותינוקות יושבין על גביהן וכוסות של אבן בידיהם הגיעו לשילוח ירדו לתוך המים ומילאום ועלו וישבו להם רבי יוסי אומר ממקומו היה משלשל וממלא מפני קבר התהום
And once they reached age seven or eight and were capable of assisting in the performance of this ritual, the priests would bring oxen there. And they would place doors on the backs of these oxen, and the children would sit upon the doors and they would hold cups of stone, which are not susceptible to ritual impurity, in their hands. When they reached the Siloam pool, they descended into the water and filled the cups with water, and ascended and sat themselves on the doors. The water in the cups was mixed with the ashes of the heifer and used for sprinkling on the impure person or vessels. Rabbi Yosei says: The children did not descend from their oxen; rather, each child from his place on the door would lower the cup with a rope and fill it with water due to the concern lest there is a grave in the depths beneath the path leading from the oxen to the pool.
ותניא ר' יהודה אומר לא היו מביאין דלתות אלא שוורים והא שוורים דאהל שאינו עשוי בידי אדם הוא וקתני ר' יהודה אומר לא היו מביאין דלתות אלא שוורים
And it is taught in a baraita that Rabbi Yehuda says: They would not bring doors; rather they would bring only oxen. The size of the spinal column and the body of the animal was sufficient to constitute a tent and therefore served as a barrier before the impurity imparted by a grave in the depths. And this is difficult, as aren’t oxen a tent that is not established by a person; and it is taught that Rabbi Yehuda says: They did not bring doors; rather they brought only oxen. Apparently, the legal status of a tent that is not man-made is that of a tent.
כי אתא רב דימי א"ר אלעזר מודה ר' יהודה כמלא אגרוף תנ"ה ומודה ר' יהודה בשקיפין ובנקיקי הסלעים
When Rav Dimi came from Eretz Yisrael to Babylonia he said that Rabbi Elazar said: Rabbi Yehuda concedes that the legal status of a tent that is not man-made is that of a tent when the tent is a fistbreadth, which is more than a handbreadth in terms of length, width, and height. It is only when the tent is less than the size of a fist that Rabbi Yehuda holds that it is not a tent. That opinion is also taught in a baraita: And Rabbi Yehuda concedes in the case of caves and deep cavities in the rocks that their status is that of a tent even though they are not man-made.
והרי דלת דיש בה כמה אגרופין וקתני רבי יהודה אומר לא היו מביאין דלתות אלא שוורים אמר אביי לא הוצרכו להביא דלתות
The Gemara asks: But a door on the back of an ox is an object that measures several fistbreadths, and it is taught that Rabbi Yehuda says: They did not bring doors but only oxen. Apparently, a door does not constitute a tent, since that is not the manner in which a tent is typically established. Abaye said in response that Rabbi Yehuda did not say that the legal status of the door is not that of a tent; rather, he said: They did not need to bring doors because the oxen themselves were sufficiently broad.
רבא אמר לא היו מביאין דלתות כל עיקר שמפני שדעתו של תינוק גסה עליו שמא יוציא ראשו או אחד מאבריו ויטמא
Rava said Rabbi Yehuda’s statement should be explained differently. They would not bring doors at all. Because a child has an exaggerated sense of self-confidence due to the width of the door, he might allow himself to move from side to side and as a result, perhaps he will extend his head or one of his limbs beyond the edge of the door and will become impure