Prohibitions Related to Fosterage (Explanation of the Rules Stipulated in the Ayah 23 of the Surah Al-Nisa)

Breast-feeding an infant is done by the mother or non-biological mother (wet nurse). Breast-feeding by non-biological mother makes marriage prohibited in specific conditions and brings about mahramiyyat and kinship. The ayah 23 of the surah Al-Nisa is the only ayah discussing this matter. This ayah proves the ruling of prohibited marriage due to milk kinship for two groups of women (mothers and foster sisters). There are wide disagreements and disputes among the Shi'a and Sunni jurisprudents and interpreters on deducing the rules pertaining to the prohibitions of fosterage as well as the interpretation and explanation of this holy ayah. The emergence of this holy ayah confirms the word of khosus al-manzilah in the prohibitions of fosterage, the application of the ruling of prohibition to the posterior (lahiq) fosterage on contract, the necessity for the breast-feeding woman to be alive, the lack of necessity of marriage contract in the time of breast feeding and the stipulation of sucking in the ruling of prohibition.