Handel's Hallelujah Chorus

The work in which the Hallelujah Chorus appears is titled "The Messiah" and clearly is in reference to Jesus Christ. Are there Old Testament references in the Hallelujah Chorus?

Indeed there are.

First, the word hallelujah itself is a transliteration of a Biblical Hebrew word meaning "praise God," hallelu yah. The "yah" is short for YHWH, or Jehovah - God's name. The hallelu is the verb part and also includes a notion of "make shine."

The phrase "and He shall reign forever and ever" first appears in Exodus 15:18, the last phrase in the Song of Moses. This part of the Exodus story also happens to include an early reference to music in the Old Testament: timbrels, dancing, and singing (Exodus 15:20-21). The words "forever" (olam) and "ever" (ad) each carry a sense of perpetuity, long duration, and futurity.