Job 15:21

A dreadful sound is in his ears - If he be an oppressor or tyrant, he can have no rest: he is full of suspicions that the cruelties he has exercised on others shall be one day exercised on himself; for even in his prosperity he may expect the destroyer to rush upon him.

A dreadful sound is in his ears - Margin, "A sound of fears." He hears sudden, frightful sounds, and is alarmed. Or when he thinks himself safe, he is suddenly surprised. The enemy steals upon him, and in his fancied security he dies. This sentiment might be illustrated at almost any length by the mode of savage warfare in America, and by the sudden attacks which the American savage makes, in the silence of the night, on his unsuspecting foes. The Chaldee renders this, "the fear of the terrors in Gehenna are in his ears; when the righteous dwell in peace and eternal life, destruction comes upon him."

In prosperity the destroyer shall come upon him - When he supposes he is safe, and his affairs seem to be prosperous, then sudden destruction comes; see 1 Thessalonians 5:3. The history of wicked people, who have encompassed themselves with wealth, and as they supposed with every thing necessary to happiness, and who have been suddenly cut off, would furnish all the instances which would be necessary to illustrate this sentiment of Eliphaz. See an exquisitely beautiful illustration of it in Psalm 37:35-36 :

I have seen the wicked in great power,

And spreading himself like a green bay-tree.

Yet he passed away, and lo he was not;

Yea, I sought him, but he could not be found.

So, also, in Psalm 73:18-20 :

Surely thou didst set them in slippery places;

Thou castedst them down into destruction.

How are they brought into desolation as in a moment!

They are utterly consumed with terrors.

As a dream when one awaketh,

O Lord, when thou awakest, thou shalt despise their image.

15:21 A sound - Even when he feels no evil, he is tormented with perpetual fears. Come upon him - Suddenly and unexpectedly.