The book of Ecclesiastes gives us a glimpse of who Jesus is in the Old Testament (O.T).

The title Ecclesiastes, means Speaker before the ekklesia (assembly). God is the speaker before the assembly, this assembly (His Church and body of believers) and so pay attention to what He has to say.

Any thing apart from God is futile (vain, vain, vain) is the key theme that pretty much rings throughout the entire book, until we come to the penultimate words in the very last chapter, as recorded in Ecclesiastes 12:13 that talks about man’s all (the chief end of man) which is to Fear God and Keep His commandments.

The next verse (Ecclesiastes 12:14) gives us the reason as to why we ought to Fear God and Keep His commandments. The reason is because, God shall bring every work under judgment, with every secret thing, whether it be good or evil.

Hebrews 9:27 tells us that it is appointed unto men once to die and then enter into judgment.

Whether good or evil, not just the evil; the faithful with the unfaithful; the faithless with those who believe in Jesus, all will be judged for our works, no exceptions whatsoever and each of us will have to give an account of our lives to be judged by the RIGHTEOUS judge (the same Judge we saw in the book of Judges).

Carefully treading on this topic, it is important for us to recognize that we are judged on our works to receive God’s reward, not his Salvation, because it is not by our works that we can be saved, but by the grace of God (in believing in Jesus Christ) alone.

With Jesus Christ as the loving Savior – there is no other way
With Jesus Christ as the righteous Judge and King – there is no escape

We are not saved by our works, but we are saved FOR good works (good works that people may see those works and glorify God the Father, who is in Heaven) as expressed by Jesus himself in Matthew 5:16

Those who have put their trust in Jesus will not be condemned, but let us not fool ourselves into thinking that we now have a license to live the way we want to and not be held accountable. James warns us of this that we should not be merely hearers of the word, but doers lest we deceive ourselves (James 1:22)

Now back to the chief end of man which is to Fear God and keep His commandments.

The fear of the Lord is the beginning of wisdom. Even Jesus feared and glorified God (John 17) giving him the reverence and awe and kept ALL the commandments of God the Father (John 15:10). So we are expected to do the same.

Infact the greatest commandment as expressed by Jesus is to Love the Lord;

How is this demonstrated?
Jesus said, People will know you are mine (aka. we belong to Jesus), if you obey Him (His commandments), for in doing so you will demonstrate your love for God. (John 15:10)
Loving God in other words is Keeping His commandments.

So in essence, to Fear God and Keep His commandments is to become wise and love God.

In Ecclesiastes, Jesus is speaker before the assembly requiring us to become wise and love God, i.e., to Fear God and Keep His commandments.