Song of Songs
From ReformedWiki.org, the wiki for Reformed Christianity
The Song of Songs, also known as the Song of Solomon, was a book of poetry written by King Solomon in the Old Testament of the Bible. The book exalts the beauty and goodness of sexual love in marriage, portraying it as pure, joyful, and a reflection of God's creative order. The poem is a celebration of physical love, but always bound by the moral and covenantal framework of marriage, reflecting the sanctity of sex as part of God's plan for human relationships, rather than something sinful or base.