Hebrews 6:13

For God promising to Abraham, to bless all nations in his seed; i.e. by the coming of Christ, swore by himself, having no greater to swear by, &c. He shews them how certain they may be of eternal happiness, unless they be slothful. First, it is God himself, who hath promised to make them happy. Secondly, he promised it with an oath; and these are two unchangeable things in God, who cannot lie. And the oath was: unless blessing, I will bless thee, &c. The sense is, unless I give thee great blessings, let me not be esteemed the true God. By this God hath given the strongest consolation to us, who have fled from the imperfect works of the former law of Moses, by believing and hoping in Christ. This hope is as a sure and firm anchor of our souls, amidst all persecutions and dangers, which will make us enter in, even within the veil, as it were into that part of the temple called the holy of holies, which was a figure of heaven, into which Christ Jesus himself entered first, by his glorious ascension after his sufferings. He entered as our high priest, and to prepare us there a place. (Witham)