“When you come into the Land which I give you then the Land shall keep a Shabbos for Hashem.” (Vayikra 25:2)
The Raavad in his introduction to the sefer Baalei Nefesh writes of a foundation that forms the basis for most mitzvos: “That man know that he has a Creator Who rules over him.”
Since Hashem “Has given the earth to the children of man” (Tehillim 115: 16) and “You have put all things under his feet ” (Tehillim 8:7) man runs the risk of thinking that he is the sole master of the world.
Therefore Hashem set up the world so that all man’s actions are governed by laws. In this way he is constantly being reminded of Hashem as his source. Hashem gave man a field for planting and commanded him that he not plow nor plant with kilayim. When harvesting man has to separate terumos and maasros. At the time of kneading his dough he separates challah… when he eats his bread he makes a brachah… and even his clothing is subject to laws and his daily schedule conforms to Shabbos and Yom Tov. (Daas Torah Rav Yerucham Levovitz)
