Yevamot 52B

ולאשה בעלמא ⁠— אין גט, מפני שאין בידו לגרשה. בעי רמי בר חמא: ליבמתו, מהו? כיון דאגידא ביה ⁠— כארוסתו דמיא, או דלמא: כיון דלא עבד בה מאמר ⁠— לא? תיקו.

But if he wrote a bill of divorce for a regular woman who has no connection to him, even if he later married her, it is not a valid bill of divorce. This is because at the time of the writing of the bill of divorce, it is not in his power to divorce her, and therefore the bill of divorce is of no consequence. All this is evident, but in light of the above halakhot Rami bar Ḥama inquires: If he wrote a bill of divorce for his yevama and did not give it to her immediately, but only after they were married, what is the halakha? Is it a valid bill of divorce or not? The Talmud clarifies the options: On the one hand, since she is tied to him she is considered like his betrothed; or perhaps, since he has not yet performed levirate betrothal with her, she is not even considered the equivalent of his betrothed, and the bill of divorce is not effective? The Talmud does not have a resolution for this and states that the question should stand unresolved.

בעי רב חנניה: כתב גט לזיקתו ולא למאמרו, למאמרו ולא לזיקתו, מהו? מאמר עילוי זיקה קא רמי, והוה ליה כמגרש חצי אשה, והמגרש חצי אשה לא עשה ולא כלום, או דלמא: האי לחודיה קאי והאי לחודיה קאי.

Rav Ḥananya inquires: If he wrote a bill of divorce for his levirate bond, by specifying in the bill of divorce that he is thereby severing the levirate bond between them, but not for his levirate betrothal, or if he wrote a bill of divorce for his levirate betrothal and stated that it is not for his levirate bond, what is the halakha? Is the levirate betrothal superimposed upon the levirate bond, so that they are considered a single, continuous link, and he is like one who divorces half a woman, and one who divorces half a woman has done nothing; or perhaps this stands on its own and that stands on its own, and he can therefore cancel either the levirate bond or the levirate betrothal separately.