Hebrews 6:13

13. Promise to Abraham To illustrate that infinite promise of God to faith which insures to the militant Church its eternal triumph, our author, as in the Epistle to the Romans, goes back to the first great recorded exemplar in the patriarchal age, Abraham.

Could swear by no greater In a proper oath we men call a higher Being to witness our words and to be ready to punish our perjury. The true oath is a solemn calling of God himself to be that witness and avenger. But, by whom shall God swear? Only by himself. So God has to take upon himself a twofoldness. He himself must be both the promiser and witness. So the solemn words, Genesis 22:16, “By myself have I sworn, saith Jehovah, that in blessing I will bless thee,” etc. And, Numbers 14:21, “As truly as I live.”