There is no mention in Genesis of God giving Abraham a commandment to keep the weekly sabbath. Man's weekly sabbath was only introduced as part of the Mosaic law.
Jesus came to fulfill the law; Mosaic Law. That fulfillment is what changed the Sabbath to Sunday; new dispensation appears since the Old Law of Moses was fulfilled.
When Jesus began his ministry he went into the desert to pray and fast. He was visited by Satan, who among others things, offered Jesus all the power and wealth of the kingdoms of the earth if Jesus would bow and serve Satan. Had Jesus taken the offer he would have become the Messiah anticipated by the Law. But Jesus refuses the offer to become something better. He wanted Satan's job as the Lord of the Earth. Satan would be thrown from heaven in a political battle; Revelations.
God created the heavens and earth in 6 days and rested on the 7th day. The seventh day symbolizes a pause in creation. God is not doing anything. He is resting and not working. Others are charge with the days's activities, as he rested. This is similar to the earthy Sabbath where hired hands need to commissioned to do your daily chores. Satan was placed in charge, as God rested. This is why he had the authority to offer Jesus the Messiah role of the Old Testament. Satan was essentially the acting God, as God rested. Law is about good and evil similar to the tree of knowledge of good and evil; Satan's tree.
Sunday is the eighth day, which is also the first day of a new work week. The first, first day, was when God said, Let there be light! and creation begins. This a time of epic Godlike creation. The eighth day, which is the first day of a second cycle, is connected to Revelations. After the 1000 reign of peace is over, the old and heavens and earth pass away, and a new universe appears; Let there be light 2.0.
God has finished his rest, and is back to work creating a new universe. The gift of the Holy Spirit changed the Sabbath to Sunday to reflect a new beginning, without the tree of knowledge of good and evil; law fulfilled. The new universe only has the tree of Life, with its twelve types of fruits and its leaves for healing the nations.
By having Sunday become the Sabbath, instead of Saturday, humans are no longer resting on their laurels, but are now witnesses to the processes of new creation. In terms of the days of the week, Sunday is connected to the Sun, while Saturday is connected to the planet god Saturn; mythical god of prosperity and time. Saturday is also connected to Satan, and his role as Lord of the Earth, as God rested on Saturday. Satan offer Jesus all the prosperity of the kingdom's of the earth. The Sun or Sunday is after God has rested/brooded and is now working again; creation is active for light and life.
Science has shown that God days and earth days are not the same thing. Why would God choose the earth to set his schedule when there is a universe 13 billions light years large. God days are different from each days; different reference frames. The Sabbath rest of God lasted from Adam and Eve and the tree of knowledge, to deep into Revelations. During the rest is when others were in charge, as God rested and brooded, his next creation. Satan was in charge in the Old and New Testament, until Revelations. Then he was no longer divinely sanctioned in heaven; thrown from heaven. A new person was groomed for the job; Jesus; child caught up to God.