Gemara

(Rav Yehudah): (Even) if a Yevamah grew up among the Yevamim, she may do Yibum. We are not concerned lest she took off the sandal of one of them

Inference: If we knew that she took off his sandal, we would be concerned!

Question (Beraisa): Whether he intended for Chalitzah, but she didn't; or if she intended but he didn't, the Chalitzah is invalid. Both must have intention.

Answer #1: Rather, Rav Yehudah taught that even if we saw that she took off his sandal, we are not concerned lest they had intention.

Answer #2: Indeed, if she took off a Yavam's sandal, we are concerned!

The Beraisa teaches that Chalitzah without intent does not permit her l'Shuk, but she is forbidden to do Yibum.

106a (Beraisa): A Chalitzah Muta'as (deceived) is valid. This is when they tell him that if he does Chalitzah she will pay him 200 Zuz.

A case occurred in which R. Chiya bar Aba found out that the Yavam wanted to do Yibum just to consume her money. He told him 'do Chalitzah, and then you may do Yibum.' After he did Chalitzah, R. Chiya told him that she cannot do Yibum, and he should now do a proper Chalitzah that will permit her l'Shuk.

Rav Papa's sister-in-law fell to an unworthy Yavam. Abaye wanted to trick him like R. Chiya bar Aba did. Rav Papa said that R. Yochanan disqualifies this. Rather, they told him that she will pay him 200 Zuz for doing Chalitzah.

Rishonim

Rif (32b) and Rosh (12:5): If a Yevamah grew up among the Yevamim, she may do Yibum. We are not concerned lest she took off the sandal of one of them. If we knew that she took off one's sandal, we would be concerned lest she intended for Chalitzah. Even though a Beraisa invalidates Chalitzah unless both intended, that is to permit her l'Shuk. She is forbidden to the brothers even without this.

Korban Nesan'el (90): The text of the Rif, Rambam and Rosh says that we are not concerned lest she intended. The text of Rashi and Tosfos (this is our text) says that we are not concerned lest they intended.

Nimukei Yosef (Reish 33a): Mid'Oraisa, both must intend for Chalitzah. When only she intended we disqualify only due to Mar'is ha'Ayin (lest people think that it was Chalitzah). Presumably, we are concerned only for removing his shoe (which is not normally done). We are not concerned if she spit at him, for people always spit. If we would be concerned, a Yevamah who grew up among the brothers could never do Yibum!

Magid Mishneh (Hilchos Yibum 4:28): The Rambam (4:14) says that spitting at the Yavam is a Chalitzah Pesulah that forbids Yibum. This must be when she spit at him in Beis Din.

Rambam (Hilchos Yibum 4:28): If a Yevamah grew up among the Yevamim, she may do Yibum. We are not concerned lest she took off the sandal of one of them when they were alone and disqualified herself to them. If we saw that she took off his sandal she is disqualified, for perhaps she intended for Chalitzah. She is not permitted l'Shuk until she does a Kosher Chalitzah.

Kesef Mishneh: Why does the Rambam say that she is disqualified lest she intended? The Gemara says that even if she did not intend she cannot do Yibum! It seems that the Rambam teaches that even if she intended, this does not permit her l'Shuk. Alternatively, if we would know that neither of them intended, she would be allowed to do Yibum.

Question (Rosh 12:11): They sent to Shmuel's father (104b) that if a Yevamah spat, she must do Chalitzah. However, we find that Amora'im (106a) tricked Yevamim into doing Chalitzah. Why was this necessary? The Yavam and Yevamah were there, they could have told her to spit at him! If the Halachah does not follow the above teaching, why did the Rif bring it?

Answer (Rosh): The Gemara said that if a Yevamah grew up among the Yevamim, and we saw that she took off the sandal of a Yavam, we would be concerned lest they had intent. Even removing his shoe does not disqualify without his intent, all the more so spitting!

Question: Above (12:5), the Rosh said that the text says that we are not concerned lest she intended! If so, the question remains! Also the Tur says that intent of one disqualifies, and if we saw that she removed a Yavam's shoe we are concerned lest they intended!

Answer #1 (Bach EH 169 DH v'Nir'eh and DH u'Fosak): The Tur means that if she removed his shoe we are concerned lest they, i.e. either of them, intended. The Rosh holds that the Amora'im hold like the first version (that even if we saw that she took off his sandal, we are not concerned lest they had intent). Alternatively, they were concerned for this version. We may not force a Yavam to do Chalitzah if according to one version he may do Yibum.

Answer #2 (Beis Shmuel 169:45): The Rosh equates spitting and removing the shoe. He holds that both of them are in Beis Din, and the Gemara says that if one of them intended it is a Pasul Chalitzah if both actions, i.e. spitting and removing the shoe, were done. If only one was done, Yibum is still permitted unless both intended. The Tur says that we are concerned lest they intended. This is when she did not spit.

Answer #3 (Taz 169:20): Above we discuss when we do not know whether or not the Yavam wants to do Chalitzah. If she intended, we are concerned that also he did, so Yibum is forbidden. When we know that he wants to do Yibum, we are not concerned.

Answer #4 (Korban Nesan'el 40): Above we discuss when the Yavam wants to do Chalitzah. If she also intended, it is a proper Chalitzah, so Yibum is forbidden. When he wants to do Yibum, we need not decree. The text of the Tur should say 'we are concerned lest she (i.e. or he) intended'.

Question (Tosfos 104b DH v'Ha): Why do we allow Chalitzas Ketanah (105b)? Why do we need "Ish" to disqualify Chalitzas Katan? A minor does not have intent!

Answer #1 (Tosfos): Sometimes a minor has intent, e.g. when Beis Din stands over him and instructs him.

Answer #2 (Chacham Tzvi 1 DH Ani): Tosfos holds that Chalitzah without intent does not forbid mid'Oraisa, only mid'Rabanan. If the intent needed for Chalitzah is like intent for Mitzvos, one must have this intent at the time. If we merely require intent like for Kinyanim, it suffices that they know that Chalitzah permits. We do not care what they intend at the time. According to this, without "Ish" we would allow Chalitzas Katan, just like a minor may receive her Get. The Rambam holds that Chalitzah without intent forbids Yibum mid'Oraisa, so "Ish" teaches that Chalitzas Katan does not forbid at all.

Maharit (brought in Chacham Tzvi DH v'Ra'isi): The Gemara requires intent of both only to exclude when they were tricked. We do not require intent for the Mitzvah. This is like Shechitah. Chachamim require only intent to cut the Simanim. They disqualify only if he intended to insert the knife in a wall. This is why the Rambam brings only the law of tricked Chalitzah, but not intent for Chalitzah.

Rebuttal (Chacham Tzvi): We cannot learn from Shechitah, for the Gemara did not say that intent for Shechitah is required. The Rambam brings the law of intent in Chalitzah.

Beis Meir (169:44): Surely intent for Mitzvos is required. The Rambam (Yibum 4:8) says that Chalitzah should be done Lishmah. Tosfos (ibid.) says that a Cheresh cannot do Chalitzah only because he cannot speak, even though he cannot make Kinyanim, even if Beis Din instructs him. If intent for Kinyanim was required, a tricked Chalitzah would not be valid, Even though the condition does not help, it would be like a mistake sale, which is invalid.

Note: It is not clear why this is different than one who made an invalid Tanai (the action stands). We do not say that if it was a Kinyan it is invalid!

Question (Aruch ha'Shulchan 169:64): Rashi (102b DH Ha) explicitly requires intent for the Mitzvah. According to the opinion that Mitzvos do not require intent, why is Chalitzah different?

Answer (Aruch ha'Shulchan): In other Mitzvos it is recognized that one does the action l'Shem Mitzvah. It is not common for one to blow a Shofar, take a Lulav or eat Matzah, if not for a Mitzvah. People constantly need to remove shoes and spit. The Torah required reciting verses in order that it will be done with intent.

Poskim

Shulchan Aruch (EH 169:44): Both of them must intend that the Chalitzah permit her l'Shuk.

Perush on Seder Chalitzah (b'Sof Siman 169, Sa'if Katan 30): Therefore, the judges tell them that she was Zekukah l'Yavam and that the Chalitzah will permit her.

Shulchan Aruch (ibid.): If she intended but not him, or vice-versa, she is not permitted. It is a Chalitzah Pesulah, and it forbids her to the brothers. Therefore, if a Yevamah grew up among the brothers and we saw that she took off the shoe of one of them, she cannot do Chalitzah, for perhaps they intended for Chalitzah. She needs a Kosher Chalitzah to permit her l'Shuk. If we did not see that she took off a Yavam's shoe, we are not concerned.

Beis Yosef (DH u'Mah she'Chosav Lefichach): The Halachah always follows the latter version.

Beis Shmuel (45): The Rif and Rambam hold like the Nimukei Yosef, who says that her intent alone in removing the shoe forbids Yibum. The Shulchan Aruch says 'perhaps they intended for Chalitzah.' This is not precise (he always rules like the Rif and Rambam against the Rosh). Perhaps the Rosh equates spitting in Beis Din to removing his shoe outside of Beis Din, but removing his shoe in Beis Din forbids Yibum even without intent. (Hagahos Ma'ase Nisim - this should say 'his intent', like the first edition of the Beis Shmuel.)

Beis Meir (ibid. DH ul'Hachi): The conclusion is that mid'Oraisa we require intent of one of them. Mid'Rabanan she is not permitted unless both of them intended.