Praying from Hebrews 6:17 relating to Immutability, Promise, Oath.

Dear God, I thank you for your unwavering counsel and your promise to your heirs. I claim the promise of your immutability and ask that you interpose with an oath to show me more abundantly your faithfulness. May your promises be fulfilled in my life, and may I always trust in your unchanging nature. Amen.

Verse: 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,
Hebrews 6:17

This is a Promise. The verse is stating that God is determined to show the heirs of the promise the unchanging nature of his counsel, and he does so by interposing with an oath.