Hebrews 6:13
For God having promised Abraham, since he had no greater one by whom to swear, swore by himself,
Hebrews 3:18
And to whom did he swear that they should not enter into his rest, but to those who believed not?
Hebrews 6:17
but God, in this wishing more abundantly to show forth to the heirs of the promise the immutability of his counsel, confirmed it by an oath:
Treasury of Scripture Knowledge
Summary
But if ye will not hear these words, I swear by myself, saith the LORD, that this house shall become a desolation.
Bible References
I
Hebrews 3:18
And to whom did he swear that they should not enter into his rest, but to those who believed not?
Hebrews 6:13
For God having promised Abraham, since he had no greater one by whom to swear, swore by himself,