וְאִם־לֹ֨א תִשְׁמְע֜וּ אֵלַ֗י לְקַדֵּשׁ֙ אֶת־י֣וֹם הַשַּׁבָּ֔ת וּלְבִלְתִּ֣י ׀ שְׂאֵ֣ת מַשָּׂ֗א וּבֹ֛א בְּשַׁעֲרֵ֥י יְרוּשָׁלִַ֖ם בְּי֣וֹם הַשַּׁבָּ֑ת וְהִצַּ֧תִּי אֵ֣שׁ בִּשְׁעָרֶ֗יהָ וְאָֽכְלָ֛ה אַרְמְנ֥וֹת יְרוּשָׁלִַ֖ם וְלֹ֥א תִכְבֶּֽה׃ (פ)
너희가 나를 청종치 아니하고 안식일을 거룩케 아니하여 안식일에 짐을 지고 예루살렘 문으로 들어오면 내가 성문에 불을 놓아 예루살렘 궁전을 삼키게 하리니 그 불이 꺼지지 아니하리라 하셨다 할지니라
Shenei Luchot HaBerit
When we read in 31,16: לעשות את השבת, the extra word את suggests that we should add a little from the weekday to the Sabbath, i.e. commence the Sabbath before sunset. The words: לא תבערו אש, "Do not make a fire" in 35,3, also hint at the statement in the Talmud that wherever we find that the Sabbath is also being desecrated, we are liable to find a conflagration (Midrash Hagadol based on Jeremiah 17,27). Observance of the Sabbath on the other hand, will lead to the redemption and the rebuilding of the Holy Temple. G–d will then be as a wall of fire for Zion, as we know from Zachariah 2,9.