“The Lord said to me: See, I have begun delivering before you Siḥon and his land; begin taking possession of his land” (Deuteronomy 2:31). “The Lord said to me: See, I have begun…” – halakha: If a person of Israel is walking on the road on the day before Shabbat and it begins getting dark, and he has money or something else in his hand, what must he do? So taught the Sages: One for whom it became dark [while he was traveling] on the road gives his purse to a gentile.
Why is it permitted for him to give it to a gentile? Rabbi Levi said: When the descendants of Noah were commanded, they were commanded regarding only seven matters, and Shabbat is not one of them. That is why they permitted him to give it to a gentile. Rabbi Yosei bar Ḥanina said: An idolater who observed Shabbat before he accepted circumcision upon himself incurs liability to be put to death.
Why? Because they were not commanded [to observe] it. What did you see that led you to say that an idolater who observed Shabbat incurs liability to be put to death? Rabbi Hiyya bar Abba said that Rabbbi Yoḥanan said: The way of the world is that when a king and a noblewoman are sitting and conversing with one another, one who comes and inserts himself between them, does he not incur liability to be put to death?
So, the Shabbat is between Israel and the Holy One blessed be He, as it is stated: “Between Me and the children of Israel [it is a sign forever]” (Exodus 31:17). That is why any idolater who comes and inserts himself between them, before he accepted circumcision upon himself, incurs liability to be put to death. The Rabbis say: Moses said before the Holy One blessed be He: ‘Master of the universe, given that idolaters were not commanded regarding Shabbat, if they observe it, will You lift Your countenance to them?’
The Holy One blessed be He said to him: ‘Do you fear this matter, as you live, even were they to fulfill all the mitzvot in the Torah, I will topple them before you.’ From where is this derived? From what we read regarding the matter: “See, I have begun delivering before you.”