מדרש אויף שמות 31:15

Another thing in Bereshit. ב & ר the beginning of the word, י & ת the end of the word, and it is a word ברית (brit) i.e. covenant, And thanks to the Word and the Sabbath, the Holy One with His blessing created the world, and from whence was the Sabbath called a covenant, when it was said to their generations an eternal covenant (Exodus 15), and the word was also called a covenant, which was said to be a covenant in your flesh (Genesis 17:13), and it was also because of the Torah that the world was created, because it remained from the word of Genesis Black fire and it is fire, and there is no fire but the Torah, which is said to be from the right hand, the fire of religion to him (Deuteronomy 32:2).

"Those who profane it shall be put to death": What is the intent of this? From (Ibid. 15) "Whoever does work on the Sabbath day shall be put to death" we know the punishment. Whence do we derive the exhortation? From (Ibid. 20:10) "And the seventh day is Sabbath to the L–rd your G–d. You shall not perform any labor."

(Exodus 31:15) "Six days will work be done." And a different verse (Ibid. 20:9) "six days shall you work, and you shall do all of your work." How are these two verses to be reconciled? — When Israel do the L–rd's will, their work will be done by others, viz. "will work be done." And thus is it written (Isaiah 61:8) "And strangers will arise and graze your sheep, and the sons of strangers, your farmers and your vintners."