John Trapp on Psalms 35:4

Verſ. 4. Let them be confounded and put to ſhame] Here David beginneth his imprecations; which yet non maledicens dixit ſed vaticinantis more praedixit, ſaith Theodoret, he doth not utter as curſing, but as propheſying rather. If we ſhall at any time take upon us thus to imprecate (as we may in ſome caſes) we muſt ſee to it, firſt that our cauſe be good. Secondly, that we do it not out of private revenge; but meerly for the glory of God. Thirdly, ut ne voculam quidem niſinobis praeunte Dei, non carnis, ſpiritu effundamus, that we utter not a ſyllable this way, but by the guidance of Gods good Spirit.