The perfection and holiness of God. Also purity of heart; moral goodness of behavior; heart and life being in obedience to God's laws.

"[Righteousness] includes all we call justice, honesty, and virtue, with holy affections; in short, it is true religion."
Noah Webster's 1828

Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?
2 Corinthians 6:14

In the verse below, 'the righteous' refers to those who are perfect and holy in God; those whose hearts and lives are in obedience to God's laws; those who are just, honest, and virtuous...

"I did not come to call the righteous, but sinners, to repentance..."
Matthew 9:13