The alternating structure of the psalm continues in verses 20 and 21, where David casts a final glance at the friend who has betrayed him. But the tone has changed, hasn't it? Earlier David was deeply pained by the betrayal. Here, having laid the matter before God and having assured himself that God is his Savior and that he will surely deliver him from such evil, David steps away from his own feelings and reflects on the wrongdoing itself. The real problem is that the man is a covenant breaker, and the reason he breaks covenant is that he is a hypocrite. He pretends one thing but plots another. He speaks peace, but actually he is devising war.
Verse 15 seems to stand alone. It is the low point of the psalm and is a prayer or wish in which David longs for the destruction of his foes. The language is important because, just as verse 9 uses words that deliberately recall the confusion of speech at the building of the tower of Babel, so here the throwback is to the destruction of Korah and his followers in the days of Moses.
Having unburdened himself of his troubled inner feelings, the psalmist now turns to the wicked who are wreaking havoc in the city. His description of this evil is in words people who live in cities in our day can readily understand (vv. 9-11).
There is a significant difference between the setting of the two earlier psalms of betrayal and this one. In Psalms 52 and 54 David is in the wilderness fleeing from his enemy Saul, a low point in his career, while in Psalm 55 he is apparently established in Jerusalem, his capital city. This must mean that Saul is dead and that David is now king. We would expect this situation to be good. David's troubles should be over. But we find that this is not the case and that David is as much troubled in his ascendancy as he was when a fugitive.
In Psalm 52 David's presence in Nob had been disclosed to Saul by Doeg the Edomite. It concerns David's betrayal by a foreigner. In Psalm 54 David has been betrayed by the people of Ziph, that is, by his own countrymen. This short series of betrayal psalms reaches a strong climax in Psalm 55 with its description of David's betrayal by an intimate friend.
