Everything according to the custom of the state/ When in Rome do as the Romans do!
In many matters, as in the relationship between a person and his friend, one should act according to the customs of the place and the country. "When you come to a city, walk in its ways."
("He who accepts a field from his friend in a place that is used to being cut, he shall cut it to the ground, he shall harrow it to the ground, he shall harrow it to the ground, he shall harrow it all after him, according to the custom of the Medina" - Baba Matzi'a 9:1)
Translation
Expression (Hebrew)
הַכֹּל כְּמִנְהַג הַמְּדִינָה
Definition (Hebrew)
בְּעִנְיָנִים רַבִּים, כְּמוֹ בַּיְּחָסִים בֵּין אָדָם לַחֲבֵרוֹ, יֵשׁ לִנְהֹג עַל פִּי מִנְהַג הַמָּקוֹם וְהַמְּדִינָה. "בָּאתָ לָעִיר- הָלַךְ בִּדְרָכֶיהָ".
("הַמְקַבֵּל שָׂדֶה מֵחֲבֵרוֹ מָקוֹם שֶׁנָּהֲגוּ לִקְצֹר יִקְצֹר לַעֲקֹר יַעֲקֹר לַחְרֹשׁ אַחֲרָיו יַחְרֹשׁ הַכֹּל כְּמִנְהַג הַמְּדִינָה"- בָּבָא מְצִיעָא ט א)