Hebrews 6:12-13

6:12 so that you may not be sluggish, but imitators of those who through faith and perseverance inherit the promises.

6:13 Now when God made his promise to Abraham, since he could swear by no one greater, he swore by himself,

Hebrews 6:15

6:15 And so by persevering, Abraham inherited the promise.

Hebrews 6:17

6:17 In the same way God wanted to demonstrate more clearly to the heirs of the promise that his purpose was unchangeable, and so he intervened with an oath,