Gittin 76A

בשלמא לרבא ⁠– רישא בדלא פריש, סיפא דפריש.

Granted, according to the opinion of Rava, the first clause in the Mishnah is speaking about when the husband did not explicitly mention a period of time, and the latter clause is referring to when he did explicitly mention a period of two years.

אלא לרב אשי ⁠– מאי שנא רישא, ומאי שנא סיפא? קשיא.

But according to the opinion of Rav Ashi, who holds that when the husband does not mention a period of time the wife can fulfill her obligation by performing the action for even a single day, it is necessary to explain that the first clause in the Mishnah is referring to when she did fulfill the condition for even one day. And therefore, what is different in the first clause and what is different in the latter clause? The Talmud states: According to Rav Ashi’s opinion this is difficult.

תנו רבנן: ״הרי זה גיטיך על מנת שתשמשי את אבא שתי שנים״, ו״על מנת שתניקי את בני שתי שנים״⁠ – אף על פי שלא נתקיים התנאי, הרי זה גט; לפי שלא אמר לה: ״אם תשמשי ⁠– אם לא תשמשי״; ״אם תניקי ⁠– ואם לא תניקי״; דברי רבי מאיר.

§ A baraita states (Tosefta 7:6): If a husband said to his wife: This is your bill of divorce on the condition that you will serve my father for two years, or he said: This is your bill of divorce on the condition that you will nurse my son for two years, even if the condition was not fulfilled it is a valid bill of divorce because he did not say to her: If you will serve my father then this will be a valid bill of divorce, and if you will not serve him it will not be a valid bill of divorce, or: If you will nurse my son then this will be a valid bill of divorce, and if you will not nurse him it will not be a valid bill of divorce. And if he did not state his condition as a compound condition, stipulating both positive and negative outcomes, the condition is void and the bill of divorce is valid. This is the statement of R' Meir.