How is Sabbath a metaphor of Jesus Christ? Matthew 11:28 (NIV) “Come to me, all you who are weary and burdened,
  and I will give you rest.
  
  Matthew 12:8 (NIV) For the Son of Man is Lord of the Sabbath.


From these verses, some preachers say that Jesus Christ is now our Sabbath spiritually and we no longer have to observe the Sabbath Day, the day is no longer important. 

How exactly is this explained?
"Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil(Matt 5:17, KJV)."

The fulfillment Jesus talks about is His perfection in lieu of our sin. We cannot live by the Law to the letter because we are sinners.

"For all have sinned, and come short of the glory of God;(Romans 3:23, KJV)."

When Christ died on the cross, he offered His perfect life as a substitution for ours. When we die, we are seen as if we are Christ. 

So do we need to honor the Sabbath? Yes! We honor the Sabbath not because we must in order to achieve salvation, but because we want to live by the example Christ set for us.