'Righteous' in the Bible

My little children, I am writing these [things] to you in order that you may not sin. And if anyone sins, we have an advocate with the Father, Jesus Christ the righteous [one],

If you know that he is righteous, you know that everyone who practices righteousness has been fathered by him.

Little children, let no one deceive you: the one who practices righteousness is righteous, just as that one is righteous.

not as Cain, who was of the evil one and violently murdered his brother. And {for what reason} did he violently murder him? Because his deeds were evil and the [deeds] of his brother [were] righteous.