Charles Ellicott Commentary Psalms 21:3

"For thou meetest him with the blessings of goodness: Thou settest a crown of fine gold on his head." — Psalms 21:3 (ASV)

You anticipate him — that is, you come to meet him. The word “prevent” is familiar in this sense in the English collect: “Prevent us, O Lord, in all our doings.” (1 Thessalonians 4:15).

The “crown” is by some identified with that won by David at Rabbah Moab. Others make it refer to a coronation. Ewald thinks of a birthday celebration. Probably no more is intended than a symbol of victory and rejoicing. Maidens were accustomed to meet a monarch returning in victory, and to offer a crown, or garland, which was a symbol of extraordinary rejoicing. (Compare to 1 Samuel 18:6; Psalms 68:11; Song of Solomon 3:11).