Sukkah, Chapter 2, Mishnah 8. The Mishnah states: "Nashim va'avadim uketanim peturin min hasukkah" - women, slaves, and minors who have not yet reached the age of bar mitzvah are not obligated to sit in the sukkah on the festival of Sukkos.
The source for the exemption of women:
The Gemara brings two sources for the exemption of women:
A derivation from a verse.
A halachah l'Moshe miSinai.
At first glance no special derivation should have been necessary, since women and slaves are exempt from every positive commandment that is time-bound, that is, any mitzvah that depends on a particular time. Here, however, there was room to say otherwise, because of the principle "teishvu k'ein taduru": the obligation to dwell in the sukkah means living in it the way a person lives in his home, and a person's way of living is together with his wife. For that reason one might have thought that women would be obligated, and therefore the verse or the halachah l'Moshe miSinai came and taught us otherwise.
"Katan she'eino tzarich l'imo chayav basukkah":
A minor who no longer needs his mother is obligated in sukkah, by virtue of the mitzvah of chinuch (education). What is the defining measure that determines that he no longer needs his mother? The Gemara distinguishes between two situations:
He does not need his mother: If he wakes up at night and calls for his mother, but when there is no response he falls silent and does not keep calling, he is considered no longer to need his mother, and he is obligated in sukkah.
He needs his mother: If he keeps calling until she comes, he still needs his mother, and he is not yet trained in the mitzvah of sukkah.
The incident with the daughter-in-law of Shammai the Elder:
The Mishnah concludes with an incident that appears to go beyond this ruling: "Ma'aseh v'yaldah kalaso shel Shammai haZaken, u'pichas es hama'azivah v'sichech al gabei hamitah bishvil hakatan". The daughter-in-law of Shammai the Elder gave birth, and she had a newborn with her. Shammai removed the ceiling and placed sechach over the bed, so that the room in the house would have the status of a sukkah for the sake of the child.
The mother herself was not obligated, since a woman is exempt from sukkah. But regarding the infant boy, Shammai the Elder was stringent, even though he was too young for the mitzvah of chinuch, and even though he was in the category of a minor who still needs his mother. Nevertheless he was stringent and required the mitzvah of sukkah to be fulfilled with him, even at the youngest of ages.
In summary: In this Mishnah we learned that women, slaves, and minors are exempt from the sukkah; that there was room to obligate women on the strength of "teishvu k'ein taduru", and the verse or the halachah l'Moshe miSinai came and taught the exemption; that a minor who does not need his mother is obligated by virtue of chinuch; and that Shammai the Elder was stringent in this even with a newborn infant.