23:1 God spoke to Moses, telling him to
23:2 speak to the Israelites and say to them: There are special times that you must celebrate as sacred holidays to God. The following are My special times:
23:3 You may do work during the six weekdays, but Saturday is a Sabbath of Sabbaths. It is a sacred holiday to God, when you shall do no work. Wherever you may live, it is God's Sabbath.
Interesting translation. It was indeed God's special time and the Sabbath is indeed God's Sabbath and not just a Sabbath for the Jews. And in any case, God at that time gave the 10 commandments to all of the House of Israel (all 12 tribes)--not just to the tribe of Judah or to Judah, Benjamin, and Levi that would later make up the southern kingdom--the Kingdom of Judah.