John 8:38

I speak that which I have seen with my Father: and ye do that which ye have seen with your father.

Jesus speaks what He has seen with His Father in heaven, while His opponents do what they have seen with their father, showing that their words and actions reflect a different father from His. Rather than refuting their false claim of never having been in bondage, the statement turns the issue from political bondage under Rome to spiritual bondage to sin.

The father they follow is the devil. Their parentage is proved by rejecting truth from God and seeking to kill Jesus because His word has no place in them. Though they are Abraham's seed according to the flesh, they do not follow Abraham's example and do not live as true children of God.

The same principle divides all humanity into children of light who obey the truth and children of darkness who reject the truth. The verse cuts to the conscience like a sword.