Failure to observe the Sabbath, thereby showing covenant unfaithfulness, will result in curse. The Lord will kindle a fire in its gates, and it shall devour the palaces of Jerusalem and shall not be quenched.
This description of the destruction of Jerusalem is very similar to how Amos describes the destruction of the nations surrounding Israel and Judah (Amos 1:4, Amos 1:7, Amos 1:10, Amos 1:12, Amos 1:14; Amos 2:2; Amos 2:5; refer to Amos 1:14 for kindle
). It is the description of a city under siege being destroyed by fire.1 Every aspect of the promised blessing mentioned will be destroyed: throne, temple and people.
27 Mais si vous n'écoutez pas quand je vous ordonne De sanctifier le jour du sabbat, De ne porter aucun fardeau, De ne point en introduire par les portes de Jérusalem le jour du sabbat, Alors j'allumerai un feu aux portes de la ville, Et il dévorera les palais de Jérusalem et ne s'éteindra point.