Hebrews 7:15-22 (ESV)
This becomes even more evident when another priest arises in the likeness of Melchizedek, who has become a priest, not on the basis of a legal requirement concerning bodily descent, but by the power of an indestructible life. For it is witnessed of him,
"You are a priest forever,
after the order of Melchizedek."
For on the one hand, a former commandment is set aside because of its weakness and uselessness (for the law made nothing perfect); but on the other hand, a better hope is introduced, through which we draw near to God.
And it was not without an oath. For those who formerly became priests were made such without an oath, but this one was made a priest with an oath by the one who said to him:
"The Lord has sworn
and will not change his mind,
'You are a priest forever.'"
This makes Jesus the guarantor of a better covenant.
One of the primary things we learn from these two chapters is the integrity of Abram. He sought peace among those whom he loved even if it meant the possibility of getting the short end of the stick. He also was trusting in God for blessings, not men.
The book of Hebrews compares Jesus to Melchizedek, whom we read about here in ch. 14. Jesus is like Mel in that he is both our priest AND king. In our lives, we need to put him in the role of priest--spiritual leader and example. But we also need to allow him the role of king of our lives--sovereign leader and worthy of honor. Check this passage out.