Néhémie 9:13 Halakha : Mishneh Torah, Sabbath & Kitzur Shulchan Arukh

Both of these two—Shabbat and idolatry—are, each one, of the same weightiness as all the other commandments of the Torah. And Shabbat is the sign between the Holy One, blessed be He, and us forever. Hence anyone who transgresses the other commandments is surely included among the evildoers of Israel. But one who desecrates Shabbat in public is surely like an idolater. So both of them are like (gentile) idolaters in all of their matters. Therefore the prophet praises [one who observes Shabbat] and says (Isaiah 56:2), "Happy is the man who does this, and the man who holds fast to it; who keeps Shabbat and does not profane it, etc." And the reward in this world—beyond the reward that is saved for the world to come—[for] anyone who observes Shabbat according to its law, honors it and delights [in] it according to his ability is already explicit in the tradition. As it is stated (Isaiah 58:14), "Then you can delight in the Lord; and I will set you astride the heights of the earth, and feed you the heritage of your father Jacob—for the mouth of the Lord has spoken."

The holy Shabbos is the great sign and covenant which the Holy One Blessed is He gave to us, to know that in six days the Almighty made the heavens and the earth and all that is in them, and abstained from work on the seventh day. This is the foundation of our faith. Our Sages of blessed memory said:¹See Talmud Yerushalmi, Maseches Nedarim 3: 9 and Rambam, Shabbos 30: 15. "Shabbos is equivalent to all the mitzvos." "Whoever keeps the Shabbos in accordance with its laws is regarded as though he fulfilled the entire Torah;"²Zohar, Beshalach 47. and "whoever desecrates the Shabbos is like one who completely denies the whole Torah."³See Maseches Chulin 5a. And so it is said in Ezra: "And You came down on Mount Sinai and You gave Your people righteous judgments and true laws … and Your holy Shabbos You made known to them."⁴Nehemiah 9: 13. According to tradition, both the books of Ezra and Nechemiah were authored by Ezra.