Arachin 2b — ערכין ב:

The non-Jew and the friend come from one word, since in both cases the korban is not his. Rashi explains why the father's korban needs a word of its own: we might have thought the heir counts as the owner.

So two mentions are left. One teaches "his korban, and not his father's," and the other includes all the partners.

And what does Rabbi Yehuda do with hamer yamir, the doubled words in Parshat Bechukotai?

He uses it for a woman: her temurah counts too.

We learned in a baraita: the whole passage of temurah is written in the masculine, "he shall not exchange it." So how do we know that a woman's temurah also counts? The pasuk adds "and if he shall indeed swap."

The Rabbanan learn the woman from the letter vav, the "and" in "and if." Rabbi Yehuda does not draw a teaching from that vav.

Another Mishnah that opens with "everyone": everyone is obligated in sukkah. Who does that add?

A child who no longer needs his mother, as the Mishnah in Sukkah 2 says. Rashi refers to Masechet Sukkah (Sukkah 28b), which describes such a child as one who wakes up and does not call out for his mother. The child's obligation is chinuch, training him in the mitzvah.

Everyone is obligated in the mitzvah of lulav: this adds a child who knows how to shake the lulav, as the Mishnah in Sukkah 3 says.

Everyone is obligated in the mitzvah of tzitzit: this adds a child old enough to put wear it (wrap it) properly; a baraita teaches this. Tosafot add that the obligation falls only on a person wearing a garment with four corners. A person who has no such garment does not have to buy one.

Everyone is obligated in the mitzvah of tefillin: this adds a child who knows how to take care of tefillin. Rabbeinu Gershom explains that he knows to keep them as the halacha requires. The baraita says his father buys him tefillin.

Everyone is obligated in re'iyah, the mitzvah to come up to the Beit HaMikdash on each of the three Regalim and be seen there, bringing an olah. This adds the chatzi eved, chatzi ben chorin, a person who is partly a slave and partly free: for example, a slave owned by two partners, one of whom freed his share. Rashi explains why a full slave is exempt: the pasuk in Parshat Mishpatim says "before the Master, Hashem," which leaves out one who has another master (of flesh and blood). The Mishnah in Chagigah 1 lists who is exempt from re'iyah.

But Ravina holds, in Masechet Chagigah 4a, that the chatzi eved is exempt from re'iyah. For him, "everyone" adds someone who limped when Yom Tov began and was healed by its second day. Rashi explains that a lame person is exempt because the Torah calls the festivals regalim, from the word for feet.

That works for the view that every day of the festival is a makeup day, tashlumin, for the day before it. On that view, which the Gemara discusses in Masechet Chagigah 9a, each day carries its own obligation, so one who was healed by the second day must bring his olah. But on the view that all the days are makeup days only for the opening day of Yom Tov, whoever was exempt at the start stays exempt. Who does "everyone" add on that view?

It adds someone blind in a single eye. This is not like the Tanna of the next baraita.

We learned in a baraita that Yochanan ben Dahavai, quoting Rabbi Yehuda, exempts from re'iyah one whose sight is gone in a single eye.

The word in the pasuk, in Parshat Mishpatim, is written so it can be read yir'eh, "he will see," and it is read yera'eh, "he will be seen." Rashi explains: the One Who comes to see, so to speak, sees with both eyes, and so the one who comes to be seen must see with both of his eyes.

Or you can say: "everyone" really does add the chatzi eved.

And what about Ravina? There is no contradiction. Ravina speaks according to the first Mishnah, and this teaching follows the later Mishnah. Rashi explains: before Beit Hillel changed their view, such a person was treated as a slave. After they changed it, we have the power to make him free, so no other master has a claim on him, and he counts as free.

This is the Mishnah in Gittin 4 (also on Gittin 41a): the chatzi eved works for his master one day and for himself the next day. So rule Beit Hillel.

Beit Shammai answered that this ruling takes care of the master but leaves the slave stuck in his situation.

He cannot marry a shifcha, a slave woman, because of his free half, and he cannot marry a free woman, because of his slave half.

Should he then stay without children? The whole purpose of Creation was pru urvu, bringing children into it, as the pasuk says in Yeshayahu: Hashem made the earth not for emptiness but to be settled.

Rather, for tikkun ha'olam, the good order of the world, we compel his master to set him free, and he writes his master a note for half of his value.

And Beit Hillel came back and taught like Beit Shammai. That is the later Mishnah the Gemara mentioned. For re'iyah, though, the Bartenura on the Mishnah in Chagigah 1 notes that the halacha is otherwise: the chatzi eved is exempt, because of the part of him that is still a slave.

Everyone is obligated in blowing the shofar: this adds a child who has reached the age of chinuch. We learned in the Mishnah (Rosh Hashanah 4) that we do not stop a child from blowing the shofar on Yom Tov. Rashi cites Masechet Yoma 82a for a dispute about that age. Tosafot answer that the dispute there is about fasting on Yom Kippur. For other mitzvot, each child is trained when he is ready for that mitzvah, as we saw with sukkah, lulav and tefillin.

Everyone is obligated in reading the Megillah, and all are valid readers of it. Who does that add? The answer is on the next amud.