It may be this:
Pesachim 51a:
יוֹצְאִים בְּקוֹרְדָּקֵיסוֹן בַּשַּׁבָּת, וְאֵין יוֹצְאִין בְּקוֹרְדָּקֵיסוֹן בַּשַּׁבָּת בְּבֵירֵי. וּמַעֲשֶׂה בִּיהוּדָה וְהִלֵּל בָּנָיו שֶׁל רַבָּן גַּמְלִיאֵל שֶׁיָּצְאוּ בְּקוֹרְדָּקֵיסוֹן בַּשַּׁבָּת בְּבֵירֵי, וְלָעֲזָה עֲלֵיהֶן הַמְּדִינָה, וְאָמְרוּ: מִיָּמֵינוּ לֹא רָאִינוּ כָּךְ. וּשְׁמָטוּם וּנְתָנוּם לְעַבְדֵיהֶן, וְלֹא רָצוּ לוֹמַר לָהֶן: מוּתָּרִין אַתֶּם.
Similarly, one may go out with wide shoes that resemble slippers on Shabbat; however, one does not go out with wide shoes in the city of Birei. And there was an incident involving Yehuda and Hillel, sons of Rabban Gamliel, who went out with wide shoes in Birei, and the people of the city denounced them and said: In all our days we have never seen that type of conduct. And Yehuda and Hillel removed their shoes, and gave them to their gentile servants, and did not want to tell the residents of the city: You are permitted to go out with wide shoes on Shabbat.