Hebrews 4-6: A Sabbath Rest

The writer of Hebrews is well acquainted with Jewish tradition and law.  He recalls the disobedience of the Israelites when they did not take God at his word that he would give them the land he had promised and so they were forced to wander for forty years until another generation entered the land.  In the same way, the gospel of Jesus is of no value if it is not accompanied with faith.  Just as God rested on the seventh day, there is rest for those people of God who believe...There remains, then, a Sabbath-rest for the people of God; for anyone who enters God’s rest also rests from his own work, just as God did from his. (Heb. 4:9-10 NIV) 

Unlike their ancestors, the Israelites, who were represented by a High Priest before the throne of God, the Hebrews to whom this letter is addressed have Jesus.  Therefore, since we have a great high priest who has gone through the heavens, Jesus the Son of God, let us hold firmly to the faith we profess. For we do not have a high priest who is unable to sympathize with our weaknesses, but we have one who has been tempted in every way, just as we are—yet was without sin. Let us then approach the throne of grace with confidence, so that we may receive mercy and find grace to help us in our time of need. - Heb. 4:15-16 NIV

These Hebrews, who were once heirs because of the promise made to Abraham and backed up by God's oath, are now heirs because of Jesus.  Because God wanted to make the unchanging nature of his purpose very clear to the heirs of what was promised, he confirmed it with an oath. God did this so that, by two unchangeable things in which it is impossible for God to lie, we who have fled to take hold of the hope offered to us may be greatly encouraged. We have this hope as an anchor for the soul, firm and secure. It enters the inner sanctuary behind the curtain, where Jesus, who went before us, has entered on our behalf. He has become a high priest forever, in the order of Melchizedek. - Heb. 6:17-20 NIV

It is impossible to rest when laboring under uncertainty.  But this one thing is certain, Jesus by being obedient became the source of eternal salvation for all who obey him and was designated by God to be high priest in the order of Melchizedek. (Heb. 5:9-10 NIV) and in doing so, made it possible for all who believe in the promise to enter into a Sabbath rest.