Psalm 35
This Psalm has the writer asking God to avenge the wrongful doing that others have done against him. We need God’s protection and should pray for it. We surely have not experienced what David had experienced when he wrote this - - active military, "I'll kill you" type of persecution. We are not actively sought out for persecution politically unless we fall victim to Facebook Trolls. In our lives the only persecution we can point to from the church is what we imagine in our heads.
Verse 28 says, " . . .and my tongue shall speak of thy righteousness and of thy praise all the day long." Some people end their prayers with these words. It seems to me they are actually praying: "If you do this, God, then I will give you praise". Two things occur to me - God cannot be bribed, it is wrong (an insult, even) to offer to pay Him for something. And second - we may well forget to praise God after He has done what we have asked; we just accept it and proceed on. Not thanking God is wrong anytime. It seems very wrong to promise Him thanks and then forget.