Kesubos chapter 3, mishnah 3. In the passage dealing with the anusah, the Torah sets out several conditions for the obligation to pay the fine: that she be a na'arah, that she be a virgin, and in addition to that - "asher lo orasah".
The precision of the verse's wording:
The verse does not say 'who is not betrothed' - meaning that she is not betrothed at present - for a woman who is betrothed right now is a married woman, and that was the subject of the previous mishnah. The meaning of "asher lo orasah" is that she never had any betrothal at all, that she never went through a process of kiddushin.
From here the mishnah's question arises: a virgin na'arah who had already been betrothed previously - what is her law? On this question the mishnah brings a dispute among the Tannaim in understanding the intent of the verse.
The wording of the mishnah:
"Na'arah shenis'arsah venisgarshah" - this refers to a virgin na'arah who was betrothed and then, after the betrothal, was divorced, and her virginity is intact. She is indeed a virgin na'arah, but she is not included in "asher lo orasah", since she has already been betrothed. What, then, is her status?
Rabbi Yose HaGlili says: "ein lah k'nas" - the entire passage of the fine does not apply to her, and that special penalty does not apply to her at all. Just as, had she not been a na'arah or had she not been a virgin, she would have been excluded from the category, so too the fact that she has already been betrothed removes her from the category of "asher lo orasah", and therefore there is no fine.
Rabbi Akiva says: "yesh lah k'nas" - the fine does exist, but the Torah's intent is that the fine belongs to her and does not go to her father. The fine is given to the father only when she never had any betrothal; once she has been betrothed, she has to a certain extent left her father's domain, and once she has left it even a single time, the fine no longer belongs to him but to her. Even though she was divorced, with regard to the fine she does not return to her father's domain and jurisdiction.
In summary: in this mishnah we learned the precise meaning of the verse "asher lo orasah" - that she never had any betrothal - and the dispute of the Tannaim concerning a na'arah who was betrothed and then divorced: according to Rabbi Yose HaGlili she has no fine at all, and according to Rabbi Akiva she does have a fine, but it belongs to her and not to her father.