The parallelism in verses 2-3 is not based on semantic repetition in the lines, but rather on the seconding line indicating consequence. The idea is that if a happens then b happens.

The psalmist’s enemies are called evildoers who assail him and try “to devour his flesh” (see Revised Standard Version footnote and New International Version). Since most languages will not be able to use the Hebrew metaphor “eat up my flesh,” the second verbal phrase is understood by some to mean slander (Moffatt, Revised Standard Version); others, however, take it in the sense of tear to pieces, destroy (Weiser, New English Bible, Traduction œcuménique de la Bible, New American Bible, Biblia Dios Habla Hoy), which seems more reasonable here.

In line c the psalmist’s enemies are called my adversaries and foes, two synonymous words which have very little difference in meaning. Care should be taken not to make it appear that these are different from the evildoers in line a, as a careless reading of Revised Standard Version might indicate. Something like New Jerusalem Bible would be better: “it is they, my foes and my enemies, who stumble and fall.”

Good News Translation has not attempted to retain the first line of the second pair of parallel lines in Revised Standard Version, my adversaries and foes, as this line only serves to repeat evildoers from line a. Translators must decide to what extent they will retain the formal aspect of such parallelism before deciding to follow Good News Translation.

They shall stumble and fall is not necessarily meant in a literal fashion; it is a vivid way of saying that they will be defeated and therefore unable to carry out their evil plans.

In verse 3a host, and war in verse 3c, indicate that the psalmist is a king facing a foreign army (so Eaton). Where host is taken to mean army, some languages have terms for soldiers, but not for such a large grouping of soldiers as an army. Here it may be possible to say, for example, “a line of men who fight” or “a large company of soldiers,” where “company” does not refer to a specific military unit, but rather to a group of unspecified size.

Encamp against me: this is language appropriate for a military maneuver; “besiege me” or “get ready to attack me” can also be used.

In some languages it may be clearer to begin line c with “and even if a war….”

In verse 3d, if the verb is intransitive, it means I will be confident (Revised Standard Version; also Good News Translation footnote, Traduction œcuménique de la Bible, New International Version, New Jerusalem Bible, Biblia Dios Habla Hoy); if taken as transitive, with the object “God” implied, it will mean “I will still trust God” (Good News Translation; so Briggs).

Quoted with permission from Bratcher, Robert G. and Reyburn, William D. A Handbook on the Book of Psalms. (UBS Helps for Translators). New York: UBS, 1991. For this and other handbooks for translators see here .