وَآتُوا النِّسَاءَ صَدُقَاتِهِنَّ نِحْلَةً ۚ فَإِن طِبْنَ لَكُمْ عَن شَيْءٍ مِّنْهُ نَفْسًا فَكُلُوهُ هَنِيئًا مَّرِيئًا (4)
(4:4) Give women their bridal-due in good cheer (considering it a duty); but if they willingly remit any part of it, consume it with good pleasure. *7
*7). In the opinion of 'Umar and Shurayh, if a woman gives up either the whole or a part of the bridal-due (mahr) in favour of her husband and later reclaims it from him then he is bound to pay it. The claim on the woman's part would be tantamount to her unwillingness to remit either the whole or a part of the bridal-due. For further details see the section entitled 'Mahr' in my book Huquq al-Zawjayn, 16th edition, Lahore, 1976, pp. 31-3 and 119-23.