Hebrews 6:13

When God gave his promise to Abraham, since there was no one greater by whom he could swear, he swore by himself.

Hebrews 3:18

And who were they to whom God swore that they should not enter upon his rest, if not those who had proved faithless?

Hebrews 6:18

For he intended us to find great encouragement in these two unchangeable things, which make it impossible for God to prove false--we, I mean, who fled for safety where we might lay hold on the hope set before us.

Treasury of Scripture Knowledge

Summary

Therefore hear ye the word of the LORD, all Judah that dwell in the land of Egypt; Behold, I have sworn by my great name, saith the LORD, that my name shall no more be named in the mouth of any man of Judah in all the land of Egypt, saying, The Lord GOD liveth.

I have sworn

Bible References

I have sworn

Hebrews 3:18
And who were they to whom God swore that they should not enter upon his rest, if not those who had proved faithless?
Hebrews 6:13
When God gave his promise to Abraham, since there was no one greater by whom he could swear, he swore by himself.