American Standard Version
Wherein God, being minded to show more abundantly unto the heirs of the promise the immutability of his counsel, interposed with an oath;

Berean Study Bible
So when God wanted to make the unchanging nature of His purpose very clear to the heirs of the promise, He guaranteed it with an oath.

Douay-Rheims Bible
Wherein God, meaning more abundantly to shew to the heirs of the promise the immutability of his counsel, interposed an oath:

English Revised Version
Wherein God, being minded to shew more abundantly unto the heirs of the promise the immutability of his counsel, interposed with an oath:

King James Bible
Wherein God, willing more abundantly to shew unto the heirs of promise the immutability of his counsel, confirmed it by an oath:

World English Bible
In this way God, being determined to show more abundantly to the heirs of the promise the immutability of his counsel, interposed with an oath;

Young's Literal Translation
in which God, more abundantly willing to shew to the heirs of the promise the immutability of his counsel, did interpose by an oath,

Hebrews 6:17 Additional Translations ...