At the end of Genesis 14, we see the only appearance of Melchizedek, who was a foreshadowing of the coming of Christ. Then in Genesis 15, we have God make his oath to Abram. Through these verses we see the goodness of God in providing a great high priest (Jesus) who can reign forever pleading our case to the father, and see the unchangeable nature of God through His promise made to Abram. That He would see it through regardless of Abram's ability to hold up any end of the agreement.