Daf Yomi - Beitzah 3 - Preparation and Shabbos

The Gemara discuses hachanah deRabbah, Rabbah’s law of preparation, which dictates that food for a holy day must be prepared prior to the holy day on a weekday. It is noteworthy that the verse where this principle is derived from states and it will be on the sixth day that they shall prepare the manna which they bring. The Medrash states that Yosef observed Shabbos in Egypt, as it is said have meat slaughtered and prepare it. Perhaps the understanding of this statement is that Yosef represents the attribute of yesod, foundation, which means that he observed the covenant of circumcision. The word for prepared is hachen, which has its root in the word kan, which means base or foundation. Thus, Yosef, being the tzaddik yesod olam, the righteous person who is the foundation of the world, corresponds to Shabbos, and the Ohr HaChaim (Vayikra 19:3) writes that regarding Shabbos and regarding Bris Milah, circumcision, the Torah writes the word os, a sign, demonstrating that one who observes one of these signs is a catalyst for observing the other sign.