Elihu had remained silent because of his youth. However wisdom is not a matter of age, but of Divine inspiration. Where the friends have failed, Elihu will succeed: there is no need to call in God.
Job 32:13 is a direct polemic against the poet, a strong assertion that the Divine speeches which follow had been better omitted (Peake).
6 And Elihu the son of Barachel the Buzite answered and said, I am young,c and ye are very old; wherefore I was afraid, and durst not shew you mine opinion.
7 I said, Days should speak, and multitude of years should teach wisdom.
8 But there is a spirit in man: and the inspiration of the Almighty giveth them understanding.
9 Great men are not always wise: neither do the aged understand judgment.
10 Therefore I said, Hearken to me; I also will shew mine opinion.
11 Behold, I waited for your words; I gave ear to your reasons,d whilst ye searched out what to say.
12 Yea, I attended unto you, and, behold, there was none of you that convinced Job, or that answered his words:
13 Lest ye should say, We have found out wisdom: God thrusteth him down, not man.
14 Now he hath not directede his words against me: neither will I answer him with your speeches.