Hebrews 6:16-20

16For men verily swear by the greater: and an oath for confirmation is to them an end of every dispute. 17In the same way God, willing more abundantly to show to the heirs of promise the immutability of his counsel, confirmed it by an oath:1 18That by two immutable things, in which it was impossible for God to lie, we might have a strong consolation, who have fled for refuge to lay hold upon the hope set before us: 19Which hope we have as an anchor of the soul, both sure and steadfast, and one which entereth into that within the veil; 20Where the forerunner hath for us entered, even Jesus, made an high priest for ever after the order of Melchizedek.