O continue your lovingkindness unto them that know you; and your righteousness to the upright in heart.
Read Chapter 36
Augustine of Hippo
14. "Show forth Thy Mercy unto them that know Thee; Thy Righteousness to them that are of a right heart" (ver. 10). As I have said, Those are of a right heart who follow in this life the Will of God. The will of God is sometimes that thou shouldest be whole, sometimes that thou shouldest be sick. If when thou art whole God's Will be sweet, and when thou art sick God's Will be bitter; thou art not of a right heart. Wherefore? Because thou wilt not make right thy will according to God's Will, but wilt bend God's Will to thine. That is right, but thou art crooked: thy will must be made right to That, not That made crooked to thee; and thou wilt have a right heart. It is well with thee in this world; be God blessed, who comforteth thee: it goeth hardly with thee in this world; be God blessed, because He chasteneth and proveth thee; and so wilt thou be of a right heart, saying, "I will bless the Lord at all times: His Praise shall be ever in my mouth."
Mercy and justice, are here of the same import. (Bellarmine) (Muis)
Deliver us from captivity, and extend thy mercies to all thy people. (Calmet)
Heart. Many who have sufficient learning, are destitute of this better quality. The right of heart are always more knowing than those who are only learned in speculation, and puffed up with pride. (Berthier)