Êxodo 31:13 Halacá: Mishneh Torah, Tefillin, Mezuzah and the Torah Scroll, The Sabbath Epistle & Mishneh Torah, Sabbath

The proper time for putting on phylacteries is when it is day and not when it is night, for it is said, "Day by day"^**Usually rendered, “from year to year”, referring to observance of the feast of Passover. (Exodus 13:10). "The ordinance" mentioned in this verse refers to the precept of phylacteries. So it is said, "And it shall be for a sign", while Sabbaths and festivals are them-also, Sabbaths and festivals are not seasons for putting on phylacteries, for selves a sign. When is the proper time in the day to put on phylacteries? At the hour when a person can see his neighbour at a distance of four cubits and recognize him. The period extends till sunset.

Here are honest witnesses that the day begins with dusk. Similarly for all the holidays and the Sabbath, for all are “appointed seasons of God, holy gatherings” (ibid. 23:4). Only the Sabbath is called “a Sabbath for God” (Exodus 20:10, Deuteronomy 5:14), for God rested during Creation. Since both the year and the day are dependent on the sun, for both motions are similar one to another, therefore the seventh year is comparable to the Sabbath day. Hence it is also written with regard to the seventh year “a Sabbath for God” (Leviticus 25:2). Therefore, just as the Sabbatical year begins with the autumn season, so the beginning of the Sabbath day is in that period of the day corresponding to autumn, which begins with dusk.

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."