Chapter 140

2021 - David is feeling threatened.  I'm sure it was not paranoia.  He asks for protection especially from the violent and the wicked, and he makes them somewhat interchangeable.  These verses:

6 I say to the LORD, You are my God; give ear to the voice of my pleas for mercy, O LORD! ... 8 Grant not, O LORD, the desires of the wicked; do not further their evil plot, or they will be exalted! Selah [Psa 140:6, 8 ESV]

Look at the contrast between these two verses.  David asks God to listen to him, because David serves the Lord, God is his God, and the wicked do not look to God.  David says God should hear his prayers, not theirs.

10 Let burning coals fall upon them! Let them be cast into fire, into miry pits, no more to rise! [Psa 140:10 ESV]  NDP

2021 - David is very creative with the prayers he prays about his enemies!

So it is ok to ask God to destroy your enemies.  Your true enemies.  But it is not ok for you to take care of their punishment on your own.

2024 - Think of the contrast here in what David says about his enemies, and what Solomon says.  21 If your enemy is hungry, give him bread to eat, and if he is thirsty, give him water to drink, 22 for you will heap burning coals on his head, and the LORD will reward you. [Pro 25:21-22 ESV].  Seems like Solomon had a different idea than his Dad did.  Another obvious contrast is that David was at war his entire reign.  God granted Solomon peace all around during his reign.  Perhaps David is talking about attacks upon his person and Solomon is talking about diplomacy.  I can see the diplomacy angle.