Does the maternal breastfeeding of her sister's son for eight consecutive hours, exceeding ten unfulfilling breastfeeds, prohibit marriage between them? And can fulfilling breastfeeds be counted within this short period?

Scholars differed regarding the number of sucklings that establish prohibition. The Hanafis, Malikis, and a narration from the Hanbalis held that prohibition is established by a single suckling. In contrast, the Shafi'is and the sound opinion of the Hanbalis stipulated five full sucklings, and this is the relied-upon opinion for fatwa.

The reference for determining a suckling is custom. If the child suckles and then clearly stops by choice, and then returns, it is counted as another suckling. If he takes the breast and sucks then leaves it, it is considered one suckling, whether he left it due to satiety or an impediment.

Accordingly, if five sucklings are completed, the woman becomes a foster mother, and marriage to her daughters is prohibited. If the completion of five sucklings is not established, it is advisable not to marry a daughter of a woman who suckled him, in order to avoid the disagreement of the scholars who hold that prohibition is established by a single suckling.