Hebrews 6:9-20 ESV
Though we speak in this way, yet in your case, beloved, we feel sure of better things—things that belong to salvation. For God is not unjust so as to overlook your work and the love that you have shown for his name in serving the saints, as you still do. And we desire each one of you to show the same earnestness to have the full assurance of hope until the end, so that you may not be sluggish, but imitators of those who through faith and patience inherit the promises.
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.” And thus Abraham, having patiently waited, obtained the promise. For people swear by something greater than themselves, and in all their disputes an oath is final for confirmation. So when God desired to show more convincingly to the heirs of the promise the unchangeable character of his purpose, he guaranteed it with an oath, so that by two unchangeable things, in which it is impossible for God to lie, we who have fled for refuge might have strong encouragement to hold fast to the hope set before us. We have this as a sure and steadfast anchor of the soul, a hope that enters into the inner place behind the curtain, where Jesus has gone as a forerunner on our behalf, having become a high priest forever after the order of Melchizedek.
ESV: English Standard Version 2016