Psalm 101 is the 101st psalm of the Book of Psalms, beginning in English in the King James Version: "I will sing of mercy and judgment". The Book of Psalms is part of the third section of the Hebrew Bible, and a book of the Christian Old Testament. In the slightly different numbering system used in the Greek Septuagint and Latin Vulgate translations of the Bible, this psalm is Psalm 102. In Latin, it is known as "Misericordiam et iudicium cantabo".^[1] It is attributed to David, and provides warnings for the wicked, while explaining the benefits the righteous will reap.^[2]

The psalm forms a regular part of Jewish, Catholic, Lutheran, Anglican and other Protestant liturgies.

According to Matthew Henry, "David was certainly the penman of this psalm", and he here "cuts out to himself and others a pattern both of a good magistrate and a good master of a family; and, if these were careful to discharge the duty of their place, it would contribute very much to a universal reformation.^[5]

• "I will sing of mercy and justice" (verse 1): God's "mercy" and "justice" go together, because when justice pronounces its righteous penalty, mercy may grant relief. As king, David knows that before he could exercise mercy and justice in His kingdom, he had to understand and extol the mercy and justice of God.^[6]

• "I will behave wisely in a perfect way" (verse 2): David determined that his reign would be marked by integrity and godliness, that is, to live a wise and holy life (perfect way), because as he came into a position of greater power, he experienced that power often exposes the flaws of character, if it does not actually help create them.^[6]

• "I will walk within my house with a perfect heart": David's righteous life had to be real in his conduct within his own house, before it could be applied in the courts of his kingdom.^[6]

• "I will set nothing wicked before my eyes" (verses 3–4): One measure of a righteous life was what one chose to set before the eyes, as the lust of the eyes is a significant aspect of the lure of this world (1 John 2:6).^[6]

• "Whoever secretly slanders his neighbor" (verse 5): To lie or speak in an evil way against another is a significant and grievous sin and the worst of it is done secretly, so David was determined to oppose all who did so ("Him I will destroy").^[6]

• "My eyes shall be on the faithful of the land" (verses 6–8): Instead of looking at those who thought themselves better than others, David preferred to look at the faithful, deciding that they would dwell with him.^[6]

• "Early I will destroy all the wicked of the land": David's determination to rule in favor of the godly, made him decide to remove the wicked early on from the city of God.^[6]