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.

Luke 1:73

This was the oath which he swore to our forefather Abraham--

Hebrews 6:16-18

Men, of course, swear by what is greater than themselves, and with them an oath is accepted as putting a matter beyond all dispute.

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, of course, swear by what is greater than themselves, and with them an oath is accepted as putting a matter beyond all dispute.
Luke 1:73
This was the oath which he swore to our forefather Abraham--

General references

Revelation 10:6
and swore by him who lives for ever and ever, who created the heavens and all that is in them, and the earth and all that is in it, and the sea and all that is in it,' that time should cease to be.