Question: A man concluded a marriage contract to an infant girl, then permitted—or ordered—his brother’s wife to breastfeed her, and she did so. The husband had fixed a dowry for this infant. By that suckling the marriage was annulled. Upon whom, then, is the dowry due? Is the named dowry due in full or only half? The intention from the outset in both the marriage and the suckling was to establish kinship between the said husband and the wet nurse—what is the ruling?
Answer—and Allah grants success: The dowry is due upon the husband, not upon his brother’s wife. His permission and order to his brother’s wife to breastfeed—while knowing that such suckling is a cause for dissolving the marriage—counts as a dissolution from his side, not from the side of his brother’s wife. She has committed no transgression—near or far; rather, her action was pure beneficence, for she carried out the husband’s purpose. Allah Most High says: “There is no blame upon the doers of good.” [al-Tawbah:91]. And He says: “Is the reward for excellence anything but excellence?” [al-Raḥmān:60]
Thus, the husband owes her full dowry, because the annulment did not come from the wife. What appears to me is that halving the dowry applies in divorce, not in annulment.
The proof is His saying: “Then if you know them to be believers, do not return them to the disbelievers; they are not lawful [wives] for them, nor are they lawful [husbands] for them. And give them [the disbelievers] what they have spent.” [al-Mumtaḥanah:10]. And His saying: “And if any of your wives has gone from you to the disbelievers, and then you retaliate, then give those whose wives have gone the like of what they spent.” [al-Mumtaḥanah:11]
As for the scholars of the madhhab—as in the section on suckling in the Sharḥ and its marginal notes—they obligate, in this very scenario, only half the dowry.
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.1