כֹּ֚ה אָמַ֣ר יְהוָ֔ה הִשָּׁמְר֖וּ בְּנַפְשֽׁוֹתֵיכֶ֑ם וְאַל־תִּשְׂא֤וּ מַשָּׂא֙ בְּי֣וֹם הַשַּׁבָּ֔ת וַהֲבֵאתֶ֖ם בְּשַׁעֲרֵ֥י יְרוּשָׁלִָֽם׃
thus saith the LORD: Take heed for the sake of your souls, and bear no burden on the sabbath day, nor bring it in by the gates of Jerusalem;
Read halakhic rulings (Jewish law) on Jeremiah 17:21: and classical halakhic sources.