Jeremiah 17:27
But if ye will not hearken unto me to hallow the sabbath day, and not to bear a burden, even entering in at the gates of Jerusalem on the sabbath day; then will I kindle a fire in the gates thereof, and it shall devour the palaces of Jerusalem, and it shall not be quenched.
By God's command Jeremiah took his stand at one of the principal entrances to Jerusalem to urge upon the people the holiness of the Sabbath day. The inhabitants of Jerusalem were losing sight of the sanctity of the Sabbath. To hallow the Sabbath day includes not bearing a burden and entering with it through the gates of Jerusalem on that day. The verse is a solemn warning against doing secular work on the Sabbath day.
Keeping the Sabbath is allegiance and obedience to God and His law, to the Lord God of their fathers, bringing lasting kingship and prosperity to the city. If Judah and Jerusalem refused to heed, a fire kindled in its gates would devour the palaces of Jerusalem, an unquenchable fire, until the city was utterly destroyed.