The mitzva of Shabbat is portrayed in both the ten commandments listed in sefer Shemot and in sefer Devarim- with a slight difference in wording. The medieval commentaries attempt to resolve this difference through a variety of explanations which shape their opinions of the very nature and essence of Shabbat. Through a discussion of these various opinions we learn about the proper method of interpreting not only the mitzva of Shabbat but also the rest of the Torah itself. 

Yemei Iyun be-Tanakh