"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.
﴿وَإِنْ أَرَدْتُمُ اسْتِبْدَالَ زَوْجٍ مَكَانَ زوج﴾ يَعْنِي: طَلَاق امْرَأَة، وَنِكَاح أُخْرَى. ﴿وَآتَيْتُمْ إِحْدَاهُنَّ قِنْطَارًا فَلا تَأْخُذُوا مِنْهُ شَيْئا أتأخذونه بهتانا﴾ أَي: ظلما ﴿وإثما مُبينًا﴾ بَينا.
يَقُول لَهُ: لَا يحل لَهُ أَن يَأْخُذ مِمَّا أَعْطَاهَا شَيْئا، إِلَّا أَن تنشز؛ فتفتدي مِنْهُ.
قَالَ مُحَمَّد: ﴿بهتانا﴾ مصدر مَوْضُوع مَوضِع الْحَال؛ الْمَعْنى: أتأخذونه مباهتين وآثمين. والبهتان: الْبَاطِل الَّذِي يتحير من بُطْلَانه.