You Prepare a Feast Before Me

In verse 5 of Psalm 23, there seems to be a change in how David describes his relationship to the Lord. While he has previously used the imagery of a sheep with his shepherd, now he changes the setting to a host preparing and serving a feast for an honored guest. While the setting has changed, though, the message of thanksgiving and joy continues forward.
Hospitality and meals were very important in Ancient Near Eastern culture, as they remain in much of the world today. In both the Psalms and Isaiah, the imagery of a feast is common, usually in the context of celebration to describe abundance and blessing. To be at a feast meant to be joyful, to be satisfied, and to be content, and that is certainly what is in mind here. David describes his enemies as being present at the feast, and while that could on one hand be a reminder that we still must be vigilant to the presence of our opponents, the reference is more likely to be reason for additional joy and celebration. To be a guest of a host meant that the host was granting his protection, and although enemies may be present, the guest is safe. In addition, because he is an honored guest, this would have been a source of frustration to the opponents, and validation to David.
In a further sign of honor, David says that the Lord anoints his head with oil. Oil was commonly used in the culture. It was often perfumed, it protected against dry skin, and it made skin shinier and more attractive. While it was not required that a host provide oil, it was recognized as a special courtesy and honor when they did, and it was typically done for especially honored guests. Furthermore, a good host would always make sure that a guest was properly fed and given plenty to drink. Honored guests would receive extra special attention in that way. The idea of a cup overflowing meant that the host was being extraordinarily gracious and kind in a further sign of the honor that the host is bestowing upon him.
It is important to remember that the enemies that are envisioned here are also assumed to be those that are our enemies because of our righteousness. To be vindicated and delivered means that one has lived in the will of God, and the justice that is received reflects God’s holiness and righteousness. When we do seek to please and follow God, then we can look confidently forward to the vindication that will come, trusting in God’s goodness and faithfulness to honor His promises, even if enemies are still around for the time being.