The Bible
Hebrews 6
Let us go on to perfection—The sons of perdition crucify Christ anew—God swears with an oath that the faithful will be saved.
3And this will we do, if God permit.
5And have tasted the good word of God, and the powers of the world to come,
13For when God made promise to Abraham, because he could swear by no greater, he sware by himself,
14Saying, Surely blessing I will bless thee, and multiplying I will multiply thee.
15And so, after he had patiently endured, he obtained the promise.
16For men verily swear by the greater: and an oath for confirmation is to them an end of all strife.