To the Jews so that the Sabbath be a sign between Yahweh and us so that we never forget that Yahweh is our God. (Ezekiel 20:12,20)
He sanctified it at creation...it was made Holy back then.
Did He sanctified it Holy for Himself?
Do you think He made it as a memorial to remind Himself? "Oh yeah...I made it..."
After the disobedience in the garden everything He created He cursed, land, creatures and man was but not the Sabbath. It remains Holy. Remember?
Like the other commandments, the sabbath is a saying or word describing what it is like with Him where He is. There is no other god where He is, no images there, no need to kill, steal, for adultery, lies or coveting where "I AM"
And oh BTW not only was Sabbath given to the whole nation of Israel not just one tribe but it is the only commandment that specifically includes to the stranger the non Israelite with them. (And even the animals)
And someday soon, halleluYah! all people will celebrate from new moon to new moon Sabbath to Sabbath in His house of prayer for all nations.
Not just one tribe who even taxed their brothers to worship there...