This verse begins with a Hebrew particle which can have the sense of Revised Standard Version‘s how much more, in which verse 18 is the base for the comparison. That is, God will trust human beings less and find even more fault in them than in angels. The verse has three lines which are all parallel. They all emphasize the frailty of human life.

Who dwell in houses of clay: human beings were formed from the dust of the earth in Genesis 2.7; 3.19; also Job 10.9; 33.6; 1 Corinthians 15.47. The figure of a house or tent representing the physical body is common in the Old Testament. Whose foundation is in the dust: the solidity of a building depends upon the firmness of its foundation, and man’s “house of clay,” which is his body, rests on nothing more substantial than dust (Psa 103.14).

If the figure dwell in houses of clay is likely to be understood as referring to people who live in mud-walled houses, it will be necessary to shift to a different figure or to say, for example, “a human being,” or “an ordinary person,” or “ordinary people whose bodies God created from clay.” If the figure of the dwelling is not kept in line a, it will not be possible to keep foundation is in the dust in line b. In that case we may sometimes say, for example, “who are nothing more than dust” or “who are weak as dust.”

The final line of this verse shifts the metaphor to another frail creature, the moth, which is used to emphasize the vulnerability of human beings. Who are crushed before the moth: this expression is to be taken to mean “who are crushed quicker than a person can crush a moth.” It fits the context to understand this line to mean “They (human beings) are crushed like a moth,” and this is the way most translators understand it. So man is crushed by God as easily as a person crushes a fragile moth. Crushed before the moth must often be restructured to say, for example, “who are as fragile as a moth” or “who die as easily as a person crushes a moth.”

Quoted with permission from Reyburn, Wiliam. A Handbook on Job. (UBS Helps for Translators). New York: UBS, 1992. For this and other handbooks for translators see here .