Gittin 72B

אי אמר רבי יוסי בעל פה, אי לא אמר.

if R' Yosei says that the date on which a document is written proves when it takes effect even when the husband stated a verbal condition as he handed it over, or if R' Yosei does not say his principle in such a case.

ומי מספקא ליה?! והתנן: ״הרי זה גיטיך אם לא באתי מכאן ועד שנים עשר חדש״, ומת בתוך שנים עשר חדש ⁠– אינו גט. ותני עלה: רבותינו התירוה להינשא.

The Talmud asks: But is Rav Huna uncertain with regard to this matter? But didn’t we learn in a Mishnah (76b): If one says to his wife: This is hereby your bill of divorce if I have not come back here from now until the conclusion of 12 months, and he died within 12 months, then it is not a valid bill of divorce because the bill of divorce does not take effect until the end of 12 months, which is after the husband’s death? As a result, she is bound by a levirate bond if her husband has no children. And it is taught with regard to that Mishnah: Our Rabbis disagree, and they rendered it permitted for her to marry, because they are of the opinion that there is no levirate bond in this case.

ואמרינן: מאן רבותינו? אמר רב יהודה אמר שמואל: בי דינא דשרו מישחא; וסברי לה כרבי יוסי, דאמר: זמנו של שטר מוכיח עליו.

And we say: Who represents the opinion cited as our Rabbis? Rav Yehuda says that Shmuel says: It is the court that permitted the consumption of oil manufactured by non-Jews, and they hold in accordance with the opinion of R' Yosei, who says: The date written in a document proves when it takes effect. Evidently, according to R' Yosei this principle applies even when the husband made a verbal condition with regard to the bill of divorce.