Verse 1
"For the conductor, with stringed music, a maskil of David."
"For the conductor" means it was given to the one who led the singing, and "a maskil" is a psalm of wisdom and understanding.
Verse 10
"Confound them, O Lord, divide their tongue, for I have seen violence and strife in the city."
A plea that God frustrate the plans of the wicked — "divide their tongue" recalls the generation of Babel, that their scheme would not succeed.
Verse 11
"Day and night they go around it upon its walls; iniquity and trouble are within it."
Without stopping, the violence surrounds the city like watchmen on the wall, and wrongdoing fills its midst.
Verse 12
"Destruction is within it; oppression and deceit do not depart from its square."
Ruin and wickedness never leave its streets — deceit means words spoken with one mouth while the heart means another.
Verse 13
"For it is not an enemy who taunts me, that I could bear; nor one who hates me who exalts himself against me, from him I could hide."
Had it been an enemy, I could have borne it; had it been a foe, I could have hidden from him. The verse prepares the heart for the painful revelation that follows.
Verse 14
"But it was you — a man like myself, my close companion and my trusted friend."
But it was you — one like me, equal in worth, my close friend, one I knew and trusted. From him came the wound, and the closeness is what makes it hurt so deeply.
Verse 15
"We who together took sweet counsel, who walked in the house of God in the throng."
Together we shared deep conversation and closeness, and went up to God's house with feeling and faith. That bond is what deepens the pain.
Verse 16
"Let death come upon them; let them go down alive to the grave, for evil is in their dwelling, among them."
A plea that justice reach those who do evil — recalling Korah and his company who went down alive into the earth, for wickedness lives within their very midst.
Verse 17
"As for me, I call to God, and the LORD saves me."
But I, facing all this pain, turn to God in prayer, trusting that He will rescue me.
This is the heart of the part: out of betrayal and pain, David turns to the one place that never disappoints — to God.
This part teaches that even when a person is wounded by the one who was closest to him, he is not left alone. All the pain, disappointment, and loneliness can be brought to God — the one place where trust is never betrayed.