Mishnayos Rosh Hashanah Perek 2 Mishnah 5

There was a large courtyard in Jerusalem, which was called Beit Ya’zek. And there all the witnesses coming to testify about the new moon would gather, and the court of seventy-one judges would examine them there. And they would prepare great feasts for them, so that they would be willing and accustomed to coming and submitting their testimony. Initially, when witnesses would arrive on Shabbat from a distant place, they would not move from there all day, as they had left their Shabbat limit, and it was consequently prohibited for them to walk more than four cubits in any direction once they had completed their mission. Concerned that this limitation would discourage witnesses from coming, Rabban Gamliel the Elder instituted that the witnesses be permitted to walk two thousand cubits in each direction. The mishna continues: And not only these witnesses are granted two thousand cubits from their new place, but this applies also to a midwife who comes to deliver a child, and one who comes to rescue Jews from a fire, from an invasion of gentile troops, from a flooding river, or from the collapse of a building. All these are considered like the inhabitants of the city where they arrive, and therefore they have two thousand cubits in each direction.

חָצֵר גְּדוֹלָה הָיְתָה בִירוּשָׁלַיִם, וּבֵית יַעְזֵק הָיְתָה נִקְרֵאת, וּלְשָׁם כָּל הָעֵדִים מִתְכַּנְּסִים, וּבֵית דִּין בּוֹדְקִין אוֹתָם שָׁם. וּסְעוּדוֹת גְּדוֹלוֹת עוֹשִׂין לָהֶם בִּשְׁבִיל שֶׁיְּהוּ רְגִילִין לָבֹא. בָּרִאשׁוֹנָה לֹא הָיוּ זָזִין מִשָּׁם כָּל הַיּוֹם, הִתְקִין רַבָּן גַּמְלִיאֵל הַזָּקֵן שֶׁיְּהוּ מְהַלְּכִין אַלְפַּיִם אַמָּה לְכָל רוּחַ. וְלֹא אֵלּוּ בִלְבַד, אֶלָּא אַף הַחֲכָמָה הַבָּאָה לְיַלֵּד, וְהַבָּא לְהַצִּיל מִן הַדְּלֵקָה וּמִן הַגַּיִס וּמִן הַנָּהָר וּמִן הַמַּפֹּלֶת, הֲרֵי אֵלּוּ כְאַנְשֵׁי הָעִיר, וְיֵשׁ לָהֶם אַלְפַּיִם אַמָּה לְכָל רוּחַ: