Hebrews 6:13

For when God made His promise to Abraham, He took an oath by Himself, since He had no one greater by whom He could take it,

Luke 1:73

the oath which He swore to our forefather Abraham,

Hebrews 6:16-18

For it is a custom among men to take oath by something greater than themselves, and an oath taken for confirmation settles any dispute among them.

Treasury of Scripture Knowledge

Summary

For when God made promise to Abraham, because he could swear by no greater, he sware by himself,

General references

Bible References

He sware

Hebrews 6:16
For it is a custom among men to take oath by something greater than themselves, and an oath taken for confirmation settles any dispute among them.
Luke 1:73
the oath which He swore to our forefather Abraham,

General references

Revelation 10:6
and swore by Him who lives forever and ever, who created the heavens and all that they contain, the earth and all that it contains, and the sea and all that it contains, that there should be no more delay,