"And if you desire to replace one wife with another," meaning: divorcing one woman and marrying another. "And you have given one of them a great amount (qintar), do not take back from it anything. Would you take it in injustice," meaning: oppression, "and manifest sin," meaning: clear.
He says to him: It is not lawful for him to take anything of what he gave her, unless she commits nusuz (rebellion/ill-conduct); then she may ransom herself from him.
Muhammad said: "Injustice (buhtan)" is a verbal noun used in the place of a state (hal). The meaning is: Would you take it while you are being unjust and sinful? And "buhtan" is the falsehood by which one is bewildered due to its falsehood.