“For when God made a promise to Abraham, since he had no one greater by whom to swear, he swore by himself, saying, ‘Surely I will bless you and multiply you'” (Hebrews 6:13-14 ESV).
This portion of Scripture refers to a historic event that took place in the life of Abraham, the well-known Biblical personality and man of faith. That account is chronicled for us in the Old Testament book of Genesis. It involves a son that had been born to Abraham as God promised earlier in Genesis 15:1-6. That son was named Isaac, and he represented the fulfillment of God’s promise to provide Abraham with an heir.
However, there came a time when Isaac was involved in a significant test of Abraham’s faith…
“Then God said, ‘Take your son, your only son, whom you love–Isaac–and go to the region of Moriah. Sacrifice him there as a burnt offering on a mountain I will show you’
…When they reached the place God had told him about, Abraham built an altar there and arranged the wood on it. He bound his son Isaac and laid him on the altar, on top of the wood. Then he reached out his hand and took the knife to slay his son.
But the angel of the LORD called out to him from heaven, ‘Abraham! Abraham!’ ‘Here I am,’ he replied. ‘Do not lay a hand on the boy,’ he said. ‘Do not do anything to him. Now I know that you fear God, because you have not withheld from me your son, your only son'” (Genesis 22:2, 9-12 NIV).
That event forms the basis for our passage from Hebrews 6:13-14 and God’s response to Abraham’s act of faith…
“‘…By Myself I have sworn, says the Lord, because you have done this thing, and have not withheld your son, your only son— blessing I will bless you, and multiplying I will multiply your descendants as the stars of the heaven and as the sand which is on the seashore; and your descendants shall possess the gate of their enemies. In your seed all the nations of the earth shall be blessed, because you have obeyed My voice'” (Genesis 22:16-18).
This has led one Biblical commentator to conclude, “God’s oaths and promises can be depended on (cf. Heb. 6:16-17). This is the theological thrust of the paragraph. Our hope is in the unchanging character of God (cf. Ps. 102:27; Mal. 3:6) and Jesus (cf. Heb. 13:8) and promises of God (cf. Isa. 40:8; 55:11).” (1)
(1) Dr. Bob Utley. Free Bible Commentary, [Hebrews 6:13] Copyright © 2014 Bible Lessons International http://www.freebiblecommentary.org/new_testament_studies/VOL10/VOL10_06.html