Allah said,

﴿وَإِنْ أَرَدْتُّمُ اسْتِبْدَالَ زَوْجٍ مَّكَانَ زَوْجٍ وَءَاتَيْتُمْ إِحْدَاهُنَّ قِنْطَاراً فَلاَ تَأْخُذُواْ مِنْهُ شَيْئاً أَتَأْخُذُونَهُ بُهْتَـناً وَإِثْماً مُّبِيناً ﴾

(But if you intend to replace a wife by another and you have given one of them a Qintar, take not the least bit of it back; would you take it wrongfully without a right and (with) a manifest sin) The Ayah commands: When one of you wants to divorce a wife and marry another one, he must not take any portion of the dowry he gave to the first wife, even if it were a Qintar of money. We mentioned the meaning of Qintar in the Tafsir of Surah Al `Imran. This Ayah is clear in its indication that the dowry could be substantial. `Umar bin Al-Khattab used to discourage giving a large dowry, but later on changed his view. Imam Ahmad recorded that Abu Al-`Ajfa' As-Sulami said that he heard `Umar bin Al-Khattab saying, "Do not exaggerate with the dowry of women, had this practice been an honor in this world or a part of Taqwa, then the Prophet would have had more right to practice it than you. The Messenger of Allah never gave any of his wives, nor did any of his daughters receive a dowry more than twelve Uwqiyah. A man used to pay a substantial dowry and thus conceal enmity towards his wife!'' Ahmad and the collectors of Sunan collected this Hadith through various chains of narration, and At-Tirmidhi said, "Hasan Sahih''. Al-Hafiz Abu Ya`la recorded that Masruq said, "`Umar bin Al-Khattab stood up on the Minbar of the Messenger of Allah and said, `O people! Why do you exaggerate concerning the dowry given to women The Messenger of Allah and his Companions used to pay up to four hundred Dirhams for a dowry, or less than that. Had paying more for a dowry been a part of Taqwa or an honor, you would not have led them in this practice. Therefore, I do not want to hear about a man who pays more than four hundred Dirhams for a dowry.' He then went down the Minbar, but a woman from Quraysh said to him, `O Leader of the Faithful! You prohibited people from paying more than four hundred Dirhams in a dowry for women' He said, `Yes.' She said, `Have you not heard what Allah sent down in the Qur'an' He said, `Which part of it' She said, `Have you not heard Allah's statement,

﴿وَءَاتَيْتُمْ إِحْدَاهُنَّ قِنْطَاراً﴾

(And you have given one of them a Qintar)' He said, `O Allah! Forgive me...' He then went back and stood up on the Minbar saying, `I had prohibited you from paying more than four hundred Dirhams in a dowry for women. So, let everyone pay what he likes from his money.''' The chain of narration for this Hadith is strong.

﴿وَكَيْفَ تَأْخُذُونَهُ وَقَدْ أَفْضَى بَعْضُكُمْ إِلَى بَعْضٍ﴾

(And how could you take it (back) while you have gone in unto each other) how can you take back the dowry from the woman with whom you had sexual relations and she had sexual relations with you Ibn `Abbas, Mujahid, As-Suddi and several others said that this means sexual intercourse. The Two Sahihs record that the Messenger of Allah said three times to the spouses who said the Mula`anah;

«اللهُ يَعْلَمُ أَنَّ أَحَدَكُمَا كَاذِبٌ، فَهَلْ مِنْكُمَا تَائِبٌ؟»

(Allah knows that one of you is a liar, so would any of you repent ) The man said, "O Messenger of Allah! My money,'' referring to the dowry that he gave his wife. The Messenger said,

«لَا مَالَ لَكَ، إِنْ كُنْتَ صَدَقْتَ عَلَيْهَا فَهُوَ بِمَا اسْتَحْلَلْتَ مِنْ فَرْجِهَا، وَإِنْ كُنْتَ كَذَبْتَ عَلَيْهَا فَهُوَ أَبْعَدُ لَكَ مِنْهَا»

(You have no money. If you are the one who said the truth, the dowry is in return for the right to have sexual intercourse with her. If you are the one who uttered the lie, then this money is even farther from your reach.) Similarly Allah said;

﴿وَكَيْفَ تَأْخُذُونَهُ وَقَدْ أَفْضَى بَعْضُكُمْ إِلَى بَعْضٍ وَأَخَذْنَ مِنكُم مِّيثَـقاً غَلِيظاً ﴾

(And how could you take it (back) while you have gone in unto each other and they have taken from you a firm and strong covenant) (Be kind with women, for you have taken them by Allah's covenant and earned the right to have sexual relations with them by Allah's Word.)