This Psalm speaks about David and his adversaries and especially about Jesus Christ and his adversaries.
The Book of Acts (Act 1:20) tells us, that it speaks also about Judas Iscariot:
"For it is written in the book of Psalms, Let his habitation be desolate, and let no man dwell therein: and his bishoprick let another take." (Psalm 69 and 109).
People, who like death, lies, who hate God, the real one, will get, what they want.
As I say - everyone of us will be destroyed - either by His word or His sword.
Evil will be destroyed - either without us, or together with us.
But the memory of evil and people, who adore and praise evil, will be cut off from the earth (verse 15). And who will be left?
What did Jesus say? (Matthew 5:2-12)
"And he opened his mouth, and taught them, saying,
Blessed are the poor in spirit: for theirs is the kingdom of heaven.
Blessed are they that mourn: for they shall be comforted.
Blessed are the meek: for they shall inherit the earth.
Blessed are they which do hunger and thirst after righteousness: for they shall be filled.
Blessed are the merciful: for they shall obtain mercy.
Blessed are the pure in heart: for they shall see God.
Blessed are the peacemakers: for they shall be called the children of God.
Blessed are they which are persecuted for righteousness' sake: for theirs is the kingdom of heaven.
Blessed are ye, when men shall revile you, and persecute you, and shall say all manner of evil against you falsely, for my sake.
Rejoice, and be exceeding glad: for great is your reward in heaven: for so persecuted they the prophets which were before you."
verse 17: "As he loved cursing, so let it come unto him: as he delighted not in blessing, so let it be far from him."
On TV and in mouth of majority of people is curse - they curse God the Father, the Lord Jesus Christ, they curse each other or even themselves (frequently heard phrase is: Let me be damned...) but how often do you hear people bless each other, God, Jesus...
You will get, what you want. I would like, that everyone would be blessed and that everyone would live forever, but some people prefer to perish forever, they like to steal, to lie, to rape, to blaspheme... What can we do?
verse 20: "Let this be the reward of mine adversaries from the LORD, and of them that speak evil against my soul."
Well, such a reward is no good, but some people like it...
verse 28: "Let them curse, but bless thou: when they arise, let them be ashamed; but let thy servant rejoice."
As I have said - people curse all the time... no matter who curses Christ and Christians, and does magic on them, God changes all those things into blessing.
Christian does not fear such curse and magic.
verse 7: "...let his prayer become sin." this reminds me of
"Pro 28:9 He that turneth away his ear from hearing the law, even his prayer shall be abomination."
"Pro 15:8 The sacrifice of the wicked is an abomination to the LORD: but the prayer of the upright is his delight."
If you hide evil in you and you don't want to expose it and you are friend of it, then nothing good will come out of your mouth, only lies and hypocrisy... only sinful things.
I know, because there was a lot of evil in me and that evil was seriously hurt, when fear of God came to me and when I have for the first time heard the Gospel of Jesus Christ.
verse 26: "Help me, O LORD my God: O save me according to thy mercy:"
It is according to thy mercy and not according to my works... which were abomination to the Lord and even his saints (the real saints - not man proclaimed ones) - don't count on their work, but on His mercy.
verse 27: "That they may know that this is thy hand; that thou, LORD, hast done it."
This reminds me of Isaiah, where he speaks about Lord Jesus Christ, especially verse 10) - Isaiah 53:1-10:
Who hath believed our report? and to whom is the arm of the LORD revealed?
For he shall grow up before him as a tender plant, and as a root out of a dry ground: he hath no form nor comeliness; and when we shall see him, there is no beauty that we should desire him.
He is despised and rejected of men; a man of sorrows, and acquainted with grief: and we hid as it were our faces from him; he was despised, and we esteemed him not.
Surely he hath borne our griefs, and carried our sorrows: yet we did esteem him stricken, smitten of God, and afflicted.
But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed.
All we like sheep have gone astray; we have turned every one to his own way; and the LORD hath laid on him the iniquity of us all.
He was oppressed, and he was afflicted, yet he opened not his mouth: he is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so he openeth not his mouth.
He was taken from prison and from judgment: and who shall declare his generation? for he was cut off out of the land of the living: for the transgression of my people was he stricken.
And he made his grave with the wicked, and with the rich in his death; because he had done no violence, neither was any deceit in his mouth.
(verse 10) Yet it pleased the LORD to bruise him; he hath put him to grief: when thou shalt make his soul an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of the LORD shall prosper in his hand.
He shall see of the travail of his soul, and shall be satisfied: by his knowledge shall my righteous servant justify many; for he shall bear their iniquities.
Jesus' resurrection was the sign to the apostles and his disciples and to all of us, that God the Father was with Jesus... About his death and resurrection speaks practically the whole Bible again and again... and still majority of people cannot see it.
verse 22: "For I am poor and needy, and my heart is wounded within me."
verse 31: "For he shall stand at the right hand of the poor, to save him from those that condemn his soul."
Jesus was poor and needy and He was saved :)
verse 2: "...they have spoken against me with a lying tongue."
They have spoken and they speak about Him with a lying tongue, but when you see, what the Bible is all about, you say to Him: "My God and My Lord, have a mercy on me..."
There is much more to be said about this Psalm, but let this suffice for now.
Let God bless you - in Jesus name I pray.