King David was a prolific poet and songwriter, and some of his work has been passed down to us through the psalms. Many of these have no event recorded with them, so at the end of David’s life, we have a large group of ‘unallocated’ psalms.
Psalm 109 shows David as the victim of slander and outright hatred by someone he thought was a friend:
Psalm 109:1–5My God, whom I praise, do not remain silent,
for people who are wicked and deceitful
have opened their mouths against me;
they have spoken against me with lying tongues.
With words of hatred they surround me;
they attack me without cause.
In return for my friendship they accuse me,
but I am a man of prayer.
They repay me evil for good,
and hatred for my friendship.
David summarised the issue as:
17–19 He loved to pronounce a curse—may it come back on him.
He found no pleasure in blessing—may it be far from him.
He wore cursing as his garment;
it entered into his body like water, into his bones like oil.
May it be like a cloak wrapped about him,
like a belt tied forever around him.
In verse 29, the curses that the enemy loved to wear as ‘a cloak’ turned into disgrace:
29 May my accusers be clothed with disgrace and wrapped in shame as in a cloak.
The same curses then became the source of judgement, giving the Accuser (Satan) something to say against him at the time of judgement:
Psalm 109:6–7 Appoint someone evil to oppose my enemy;
let an accuser [Satan] stand at his right hand.
When he is tried, let him be found guilty,
and may his prayers condemn him.
There were some other very negative things David declared over this enemy (see verses 8–15), and it is likely that David was listing the curses this enemy had made over David, with the obvious pleading that the enemy would experience his own curses (presuming this enemy would never repent).
This is consistent with Jesus’ teaching that we will all be judged by our own words (and, of course, our actions):
Matthew 12:35–37 A good man brings good things out of the good stored up in him, and an evil man brings evil things out of the evil stored up in him. But I tell you that everyone will have to give account on the day of judgment for every empty word they have spoken. For by your words you will be acquitted, and by your words you will be condemned.
We’ll also be judged by the judgement we pour out on others:
Matthew 7:2 For in the same way you judge others, you will be judged, and with the measure you use, it will be measured to you.
Of course, anyone can repent of their sins and be forgiven, but that would be another whole new topic.