بسم اللہ الرحمن الرحیم

:الجواب وباللہ التوفیق

It is an abomination “makruh” for a married woman to breastfeed a child without her husband's permission. However, if the child is hungry and is panting because of hunger, in that situation it is permissible to breastfeed even without the permission of the husband. 

It is also permissible for an unmarried woman to donate her milk to a child and feed him/her. However, in both cases, the name of the child and of the woman who breastfed the child should be recorded. And both of them should be made aware of this special relationship, to avoid any unlawful relationship resulting from future marriages. 

It should be noted that formal collection and storage of milk or depositing it in a milk bank, as is done in Western countries, is not permissible in Islam.

یکرہ للمرأۃ ان ترضع صبیا بلا اذن زوجھا الا اذا خافت ھلالہ۔(شامی، کتاب النکاح: ۳؍۲۱۳)

والبکر اذا نزل لھا لبن تعلق بہ من الحرمۃ ما یتعلق بلبن الثبب (المحیط البرھانی:۴؍۹۷)

المستفاد: والواجب علی النساء أن لا یر ضعن کل صبی من غیر ضرورۃ واذا ارصفن قلیحفظق ذلک ولیتھر نہ وکتبنہ احتیاطا۔(شامی : ۴؍۲۹۶)

فقط واللہ اعلم بالصواب