Hebrews 2:2

2:2 For if the message spoken through angels proved to be so firm that every violation or disobedience received its just penalty,

Hebrews 6:16

6:16 For people swear by something greater than themselves, and the oath serves as a confirmation to end all dispute.

Hebrews 12:4

12:4 You have not yet resisted to the point of bloodshed in your struggle against sin.