Gittin 77A

לכי נפקא קאמר לה, וכי מיית בליליא ⁠– הוי גט לאחר מיתה.

he is saying to her that it will be valid once the sun comes out in the morning. And if the husband dies during the night, before sunrise, then this will be a bill of divorce after his death and is therefore invalid.

״על מנת שתצא חמה מנרתיקה״⁠ – מעכשיו קאמר לה, דאמר רב הונא אמר רב: כל האומר ״על מנת״ כאומר ״מעכשיו״ דמי.

But if he said to her: On the condition that the sun will emerge from its sheath, then he is saying to his wife that the bill of divorce will take effect retroactively from now once the sun emerges. As Rav Huna says that Rav says: Anyone who states a condition employing the language: On the condition, is like one who states: The agreement will take effect retroactively from now.

לא נחלקו אלא ב״אם תצא״⁠ – מר סבר לה כרבי יוסי, דאמר: זמנו של שטר מוכיח עליו, והוה ליה כ״מהיום אם מתי״, כ״מעכשיו אם מתי״; מר לא סבר כרבי יוסי, והוה ליה כ״אם מתי״ גרידא.

The tanna’im disagreed only in the case of one who said to his wife: This will be your bill of divorce if the sun emerges from its sheath, and the husband died during the night. One Sage, referred to as: Our Rabbis, holds in accordance with the opinion of R' Yosei, who says that the date written in a document proves when it takes effect, and it is as if the husband said: From today if I die, or as if he said: From now if I die. And one Sage, the unattributed tanna of the Mishnah, does not hold in accordance with the opinion of R' Yosei, and it is as if the husband said only: If I die, in which case the bill of divorce is not valid because it cannot take effect after the husband’s death.