The book of Ecclesiastes (Hebrew: Kohelet, Qoheleth), attributed to Solomon. Not to be confused with the apocryphal book of Ecclesiasticus (also known as the Wisdom of Jesus ben Sirach).
While the book has traditionally been ascribed to Solomon, the claim is not strongly made in the book itself (1:1, 12, speaking only of "son of David" who was "king in Jerusalem").
Claims have often been made that the Hebrew language of the book points to a much later point in biblical history. Likewise, its world of thought has resonances with the Stoic tradition in the early Hellenistic period.