“For men verily swear by the greater: and an oath for confirmation is to them an end of all strife.”
King James Version (KJV)
6:16 Men generally swear by him who is infinitely greater than themselves, and an oath for confirmation, to confirm what is promised or asserted, usually puts an end to all contradiction. This shows that an oath taken in a religious manner is lawful even under the gospel: otherwise the apostle would never have mentioned it with so much honour, as a proper means to confirm the truth
Heb 6:16 For men verily swear by the greater. When men make a solemn oath in order to settle a fact or covenant beyond controversy they usually swear in the name of God. God, however, could swear by no one greater than himself (Heb 6:13).