Shabbat and Circumcision
The Shabbat, according to Ezekiel 20:12 is God's sign ("ot") between Him and His people. It states, "Moreover also I gave them my shabbats, to be a sign between me and them, that they might know that I am the LORD that sanctify them." The Shabbat was instituted on the seventh day of creation for all mankind, and God did three things as our example in Genesis 2:1-3... 1) He rested from all work 2) He blessed the Shabbat, and 3) God sanctified the seventh day, which means He set it apart for only Holy use. The ten commandments in Exodus 20:8-12 explain further that, "six days shall you labor and do all your work, but the seventh day is the Shabbat of the Lord your God, in that day you shall do no work".
Read more about this topic: Jewish Symbolism