Psalm 51/Notes/Lexical.v. 16.551702

צִדְקָתֶךָ can refer to a state of righteous character or a concrete right(eous) act (cf. v. 21). In parallel with תְּהִלָּה (v. 17), both interpretations are possible here. If forgiveness of David's bloodguilt incurred from the murder of Uriah is in view in v. 16a, it is hard to see why such forgiveness (i.e., the concrete act) would be called "righteous." On the other hand, if the psalmist desires deliverance from violence perpetrated by others, then such deliverance could naturally be described as a righteous act. Regardless of whoever is doing the bloodshed, praise for God's righteous character would be appropriate, and this is preferred here.