While God 'kept' the first sabbath, there is NO evidence that He gave it to people then - Gen. 2:3
The scriptures do NOT tell us that Adam, Noah, Abraham or Jacob kept the sabbath (on the contrary, such commandments were NOT given to the fathers of the generation of the Exodus - Deut. 5:1f)
The first example of people who were given the sabbath is the Israelites when they camped at Mount Sinai - Exodus 16:4,5, 22-30.
God made known to the Israelites the sabbath at Mount Sinai, through the hand of Moses - Nehemiah 9:13-14.
God gave the sabbaths when the Israelites were in the wilderness - Exodus 20:10-12.
He gave them that day in which He Himself had rested at the beginning - Exodus 20:11, 31:17