This song is unique among the psalms. It probably wasn't used in the morning worship of Israel. It was a psalm specifically penned for the people to sing at a royal wedding. They were to sing it to the royal couple.
But for us, as we consider that the present King of God's people, the King of the Church, is our Lord Jesus Christ, this psalm is therefore a messianic song, a song to be sung to the King in all ages by the people of God, the bride of Christ.
As you would expect, it's a joyous song - it gives its writer and singers great joy to sing it. They express this joy by singing, "My heart is overflowing with a good theme; I recite my composition concerning the King; my tongue is the pen of a ready writer!"
Then, with such a joyful introduction, the actual song begins by addressing the groom. To Him they sing, "You are fairer than the sons of men; grace is poured upon Your lips; therefore God has blessed You forever!" So the King is praised for His "lips," for the way He speaks and for the words He says. His words are so wonderful that He is to be blessed forever. The words of our Lord Jesus Christ are indeed such words!
Then the people sing, "Gird on Your sword upon Your thigh, O Mighty One." So the people encourage their King to be ready to lead them in battle. And their song says that His warfare will be prosperous because of His "truth, humility, and righteousness," and His enemies shall fall under Him.
In fact, not only will His enemies fall under Him, but His Kingdom will be an eternal kingdom! And it'll be a righteous, glorious kingdom, a kingdom in which all His judgements will be beautiful because of their righteousness! In fact the people sing that their King "loves righteousness and hates wickedness," and His God therefore will fill Him with gladness more than all other human beings! The glory of His reign is described by a similitude of garments scented with myrh, aloes, and cassia, and of ivory palaces, waiting women who are king's daughters, and a queen at his right hand in gold from Ophir. In other words, His reign will result in a glorious and eternal kingdom, a kingdom in which His Bride is resplendent in the glory He supplies.
Having praised the King, the song is then directed to the bride. It encourages her to forget her own people and her father's house, because the King will greatly desire her beauty. She is to worship Him and Him alone, and the result will be that the world she forgot and left behind will bring gifts and seek her favor!
Living within the palace of her Husband, her clothing will be "woven with gold (holiness)," and she will in fact be brought to the King in robes of many colors. In such glorious array, then, she will enter the majestic palace of the King!
The results of this royal wedding will be that, instead of her worldly relations, she shall have sons who will be "princes in all the earth," and her name will be "remembered in all generations!"
It's a beautiful song, a song sung to the King and His bride, a song that should indeed also be sung by the bride of Christ, the Church, a song that praises her King and encourages her people, a song about her wonderful garments of righteousness and about her "sons" - those who believe and obey her testimony. It's a song that should bring with it thoughts of the glorious and eternal kingdom of which she is even now a part! This is a song, which WE can sing with JOY!