Hebrews 6:13

For when God made a promise to Abraham, since he had no one greater by whom to swear, he swore by himself,

Luke 1:73

the oath which he swore to our father Abraham:

Hebrews 6:16-18

Men swear by one greater than themselves, and in all their disputes the oath is final for confirmation.

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
Men swear by one greater than themselves, and in all their disputes the oath is final for confirmation.
Luke 1:73
the oath which he swore to our father Abraham:

General references

Revelation 10:6
and swore by him who lives for ever and ever, who created heaven and the things in it, the earth and the things in it, and the sea and the things in it, that there will be no more delay,