Yevamot 105A

רקקה ולא קראה ⁠— חליצתה כשירה, רקקה ולא חלצה ולא קראה ⁠— חליצתה פסולה. קראה ולא רקקה ולא חלצה ⁠— אין כאן בית מיחוש.

spit and did not recite the verses, her ḥalitza is valid. If she spat but did not remove the shoe and did not recite the text, her ḥalitza is disqualified. If she recited the verses but did not spit or did not remove the shoe, there is no doubt that she has done nothing, and her action has no halakhic significance.

מני? אילימא רבי אליעזר: חלצה ולא רקקה ולא קראה חליצתה כשירה? והא אמר רבי אליעזר: ״ככה יעשה״, דבר שהוא מעשה מעכב! אלא פשיטא רבי עקיבא, וקתני: רקקה ולא חלצה ולא קראה ⁠— חליצתה פסולה. למאן?

The Talmud clarifies: Who is the author of the baraita? If we say it is in accordance with the opinion of R' Eliezer, could it be that he would hold that if she removed the shoe but did not spit or did not recite the verses, her ḥalitza is valid, as stated in the baraita? But didn’t R' Eliezer say: The phrase “so should it be done” (Deuteronomy 25:9) indicates that any element of the ḥalitza process that constitutes an action is indispensable; therefore spitting is necessary. Rather, it is obvious that the baraita is in accordance with the opinion of R' Akiva, and he teaches at the end of the baraita that if she spat but did not remove the shoe or did not recite the text, her ḥalitza is disqualified. The Talmud clarifies: To whom is the yevama disqualified from marrying after such a ḥalitza?

אילימא לעלמא, פשיטא! מי הויא חליצה דאישתריא לעלמא? אלא לאו לאחין, שמע מינה.

If we say that R' Akiva means to teach us that she is disqualified from marriage to everyone in the world, this is unnecessary, as it is clear that spitting alone will not permit her to marry any stranger. It is obvious that her ḥalitza is invalid, as did any ḥalitza take place in order for her to be permitted to a stranger? Rather, is it not clear that R' Akiva is ruling that she is disqualified from marriage to the brothers? Learn from here that R' Akiva also thinks that spitting alone disqualifies her from marriage to the brothers, which is not in accordance with the previous assumption with regard to his opinion.