Paul said to his Hebrew brethren, that God might more abundantly show unto the heirs of promise the immutability of His counsel, He confirmed it by an oath. He also exhorts them, who, through faith and patience inherit the promises.

Notwithstanding, we (said Paul) have fled for refuge to lay hold upon the hope set before us, which hope we have as an anchor to the soul, both sure and stedfast, and which entereth into that within the vail, yet he was careful to press upon them the necessity of continuing on until they, as well as those who then inherited the promises, might have the assurance of their salvation confirmed to them, by an oath from the mouth of Him who could not lie; for that seemed to be the example anciently, and Paul holds it out to his Hebrew brethren as an object attainable in his day.

And why not? I admit that by reading the Scriptures of truth the Saints, in the days of Paul, could learn, beyond the power of contradiction, that Abraham, Isaac, and Jacob, had the promise of eternal life confirmed to them by an oath of the Lord, but that promise or oath was <​no​> assurance to them of their salvation; but they could by walking in the footsteps and continuing in the faith of their fathers, obtain, for themselves an oath for confirmation that they were meet to be partakers of the inheritance, with the Saints in light.