Reference for Gittin 7:7
הֲרֵי זֶה גִטֵּךְ אִם לֹא בָאתִי מִכָּאן וְעַד שְׁלֹשִׁים יוֹם, וְהָיָה הוֹלֵךְ מִיהוּדָה לַגָּלִיל, הִגִּיעַ לְאַנְטִיפַּטְרֶס וְחָזַר, בָּטֵל תְּנָאוֹ. הֲרֵי זֶה גִטֵּךְ אִם לֹא בָאתִי מִכָּאן עַד שְׁלֹשִׁים יוֹם, וְהָיָה הוֹלֵךְ מִגָּלִיל לִיהוּדָה, וְהִגִּיעַ לִכְפַר עוֹתְנַאי וְחָזַר, בָּטֵל תְּנָאוֹ. הֲרֵי זֶה גִטֵּךְ אִם לֹא בָאתִי מִכָּאן עַד שְׁלֹשִׁים יוֹם, וְהָיָה הוֹלֵךְ לִמְדִינַת הַיָּם וְהִגִּיעַ לְעַכּוֹ וְחָזַר, בָּטֵל תְּנָאוֹ. הֲרֵי זֶה גִטֵּךְ כָּל זְמַן שֶׁאֶעֱבֹר מִכְּנֶגֶד פָּנַיִךְ שְׁלֹשִׁים יוֹם, הָיָה הוֹלֵךְ וּבָא, הוֹלֵךְ וּבָא, הוֹאִיל וְלֹא נִתְיַחֵד עִמָּהּ, הֲרֵי זֶה גֵט:
(If he said:) "This is your get if I do not come from now until thirty days," and he went from Yehudah to the Galil — if he reached Antipatras and he returned, his condition is voided. [The gemara explains this Mishnah as relating to an instance where he makes two conditions: 1) If I come to the Galil, it is to be a get immediately; 2) if I do not come to the Galil — if I do not return before thirty days, it is to be a get; if not, it is not to be a get. If he went and reached Antipatras, the end of the land of Judah and returned within thirty days, the get is void. For he did not reach the Galil, and he did not tarry thirty days.] (If he said:) "This is your get if I do not come from now until thirty days," and he went from the Galil to Yehudah — if he reached Kfar Otnai [which is at the end of the border of the Galil], and he returned, his condition is voided. (If he said:) "This is your get if I do not come from now until thirty days," and he went abroad — if he reached Acco [which is at the end of the border of Eretz Israel] and returned [within thirty days], his condition is voided, [for he did not go abroad and he did not tarry thirty days.] (If he said:) "This is your get if I go thirty days without seeing your face" — if he went and came, went and came [afterwards — if thirty days passed without his seeing her face, it is a get. And we do not say that since in the beginning he came and went there is reason to suspect that he might have effected a reconciliation and voided the get, for] since he was not together with her [in the time he came and went, we do not suspect that he might have effected a reconciliation, and when the condition is fulfilled and he goes thirty days without seeing her face,] it is a get. [The gemara explains that he says at the time of the condition: "It is with this understanding that I give her the get — that she be believed by me as a hundred witnesses if she says that I did not come and stay together with her and effect a reconciliation." And this is the halachah. For if he did not say this at the time of the condition, we fear that he might come and protest and say that he had effected a reconciliation.]