the guarantee

 The book of Hebrews is a masterful presentation of the best news ever. It tells of a new covenant.  I like the specific way the author mentions it.  He is the mediator of a new covenant.  He brought it to pass! It is neat to see how he delivers it from chapters 8-13.  Here are the references. Heb. 8:6–10; 9:15; 12:24; 13:20.  This "mediator" became our Savior! The writer actually introduced this in chapter 7. 
 Heb. 7:22    Because of this oath, Jesus has also become the guarantee of a better covenant.
The "oath" was the sinless life that he lived on the earth, the efficacious sacrifice on the cross and His bodily resurrection from the dead.  
True redemption for all who believe!  Praise God!