Final answer:
Elihu is not one of the three friends mentioned at the beginning of the Book of Job, but a younger man who speaks later in the narrative.
Step-by-step explanation:
In the Book of Job, Elihu is none of the three friends mentioned at the beginning of the book. The three friends of Job who visit him to offer comfort during his trials are Eliphaz, Bildad, and Zophar.
Elihu, however, is introduced later in the narrative, starting in Job 32, as a younger bystander who has been listening to the discourse between Job and his friends. Elihu's speeches take up chapters 32 through 37, and he is critical of both Job and his three friends for the positions they have taken.