Avodah Zarah 63A

ליחול עלה איסור אתנן למפרע! אמר רבי אליעזר: כשקדמה והקריבתו.

the prohibition with regard to payment to a prostitute should apply to the payment retroactively. R' Eliezer says: The baraita is referring to a situation when she sacrificed the payment in the Temple first, before the sex took place.

היכי דמי? אי דאמר לה: ״קני ליך מעכשיו״⁠ — פשיטא דשרי, דהא ליתיה בשעת ביאה, ומתנה בעלמא הוא דיהיב לה!

The Talmud asks: What are the circumstances of such a situation? If the circumstances are that he said to her: Acquire this payment from now, it is obvious that it is permitted to sacrifice it, as it is not extant as payment at the time of the sex, and it is merely a gift that he gave her. It would not be necessary for the baraita to state this.

ואי דלא אמר לה ״קני ליך מעכשיו״, היכי (מצי) [מציא] מקרבה? ״ואיש כי יקדש את ביתו קדש״ אמר רחמנא, מה ביתו ברשותו, אף כל ברשותו.

And if the circumstances are that he did not say to her: Acquire this payment from now, how can she be allowed to sacrifice it? God states in the Torah: “And when a man should sanctify his house to be holy to YHWH” (Leviticus 27:14), from which it is derived that just as one’s house is in his possession, so too, any item that a person wishes to consecrate must be in his possession. The prostitute cannot consecrate an animal that is not in her possession.

אלא, דאמר לה: ״להוי גביך עד שעת ביאה, ואי מיצטריך ליך קני מעכשיו״.

Rather, the baraita is referring to a situation where he said to her: Let the animal be with you until the time of sex, and if you need it in the meantime, acquire it from now. The baraita teaches that in this situation she may sacrifice her payment as an offering.

בעי רב הושעיא: קדמה והקדישתו, מהו? כיון דאמר מר: אמירתו לגבוה כמסירתו להדיוט, כמאן דאקריבתיה דמי, או דלמא השתא מיהא הא קאי ואיתיה בעיניה?

Rav Hoshaya raises a dilemma: If she consecrated it first, before the sex, what is the halakha? Since the Master said that declaration to the Most High is equivalent to transfer to an ordinary person, i.e., a spoken consecration of an item to the Temple is deemed, in terms of acquisition, like the legal transfer of an item to a person, therefore, since she consecrated it by speech, is it considered tantamount to having sacrificed it, and consequently it would be permitted to sacrifice it? Or perhaps should it be reasoned that now, at the time of the sex, in any event, the animal is extant, i.e., it was not actually sacrificed, and therefore it is prohibited to sacrifice it?