HEBREWS 6:11-13 NKJV
And we desire that each one of you show the same diligence to the full assurance of hope until the end, that you do not become sluggish, but imitate those who through faith and patience inherit the promises. For when God made a promise to Abraham, because He could swear by no one greater, He swore by Himself,
HEBREWS 7:1-10 NKJV
For this Melchizedek, king of Salem, priest of the Most High God, who met Abraham returning from the slaughter of the kings and blessed him, to whom also Abraham gave a tenth part of all, first being translated “king of righteousness,” and then also king of Salem, meaning “king of peace,” without father, without mother, without genealogy, having neither beginning of days nor end of life, but made like the Son of God, remains a priest continually. Now consider how great this man was, to whom even the patriarch Abraham gave a tenth of the spoils. And indeed those who are of the sons of Levi, who receive the priesthood, have a commandment to receive tithes from the people according to the law, that is, from their brethren, though they have come from the loins of Abraham; but he whose genealogy is not derived from them received tithes from Abraham and blessed him who had the promises. Now beyond all contradiction the lesser is blessed by the better. Here mortal men receive tithes, but there he receives them, of whom it is witnessed that he lives. Even Levi, who receives tithes, paid tithes through Abraham, so to speak, for he was still in the loins of his father when Melchizedek met him.