If your language has a way of showing that this is the way one person would speak strongly to another, different from a general rule that people are supposed to obey, you should use it here.
grind into powder. This is a metaphor for "treat unjustly." (See: [[rc://en/ta/man/translate/figs-metaphor]])
# the needy
This nominal adjective can be translated as a noun phrase. AT: "any needy person" or "any person who does not have what he needs to live" (See: [[rc://en/ta/man/translate/figs-nominaladj]])
# at the gate
The place where people bought and sold items and settled legal arguments is used as a metonym for business and legal activity. AT: "in court" (See: [[rc://en/ta/man/translate/figs-metonymy]])
# Yahweh will plead their case
The metaphor is of a lawyer defending the needy in front of a judge. AT: "Yahweh will defend the needy from those who oppress them" or "Yahweh will see that the needy receive justice" (See: [[rc://en/ta/man/translate/figs-metaphor]])
# he will rob of life those who robbed them
Yahweh is not a thief, but like a thief he will take life from those who do not choose to give it. AT: "he will destroy those who oppress poor people" (See: [[rc://en/ta/man/translate/figs-metaphor]])