The first time the Bible uses the word Sabbath is found in the book of Exodus in chapter 16. There it is defined as being the seventh day of the week. We know from Genesis that the seventh day was a day of rest for God.
Exodus 16:26 (NASB)
26 Six days you shall gather it, but on the seventh day, the sabbath, there will be none.
The last time the word Sabbath is used in the Bible is found in Hebrews chapter 4 verse 9. There it is used in a prophecy about a future Sabbath rest.
Hebrews 4:9 (NASB)
9 There remains therefore a Sabbath rest for the people of God.
Jesus spoke of the end times and stated that the Sabbath would still be in effect at that time.
Matthew 24:14 and 20 (NASB)
14 And this gospel of the kingdom shall be preached in the whole world for a witness to all the nations, and then the end shall come. ... 20 But pray that your flight may not be in the winter, or on a Sabbath;
Genesis 2:1 to 3 (NASB) (The first account of the seventh day.)
2:1 THUS the heavens and the earth were completed, and all their hosts. 2 And by the seventh day God completed His work which He had done; and He rested on the seventh day from all His work which He had done. 3 Then God blessed the seventh day and sanctified it, because in it He rested from all His work which God had created and made.
Exodus 20:8 to 11 (NASB) (The commandment for the Sabbath)
8 Remember the sabbath day, to keep it holy. 9 Six days you shall labor and do all your work, 10 but the seventh day is a sabbath of the LORD your God; in it you shall not do any work, you or your son or your daughter, your male or your female servant or your cattle or your sojourner who stays with you. 11 For in six days the LORD made the heavens and the earth, the sea and all that is in them, and rested on the seventh day; therefore the LORD blessed the sabbath day and made it holy.
The Bible is consistent from start to finish regarding the Sabbath.
Exodus 31:13 (GNB)
13to say to the people of Israel, Keep the Sabbath, my day of rest, because it is a sign between you and me for all time to come, to show that I, the LORD, have made you my own people.
2014 Jacques Gauvin