# Suppose that

"When" or "If"

# an unrighteous witness

"a witness who intends to harm someone else"

# rises up against any man to testify against him of wrongdoing

Here "rise up" means to stand up in court and speak against someone to a judge. Alternate translation: "tells the judge that a man sinned in order to get the man in trouble" or "tells the judge that a man sinned, so the judge will punish him" (See: [[rc://en/ta/man/jit/figs-idiom]])