What does Jeremiah 17:27 mean?

But if you don't listen to me and keep the Sabbath holy, and if you keep carrying loads through Jerusalem's gates on the Sabbath, I'll set its gates on fire. The fire will burn down Jerusalem's palaces and won't be put out.' Jeremiah 17:27 - Modern Text Bible

(If they ignore God's warning, disaster will come. The city will be destroyed by fire as a result of their disobedience.)