Judamah al-Asadiyyah reported that she heard the Messenger of Allah ﷺ say, "I had nearly resolved to forbid intercourse with a nursing wife, until I recalled that the Romans and Persians do this and it brings no harm to their children."Malik explained that ghilah refers to a man having relations with his wife while she is breastfeeding.
حدثنا القعنبي عن مالك عن محمد بن عبد الرحمن بن نوفل أخبرني عروة بن الزبير
عن جدامة الأسدية أنها سمعت رسول الله ﷺ يقول لقد هممت أن أنهى عن الغيلة حتى ذكرت أن الروم وفارس يفعلون ذلك فلا يضر أولادهم قال مالك الغيلة أن يمس الرجل امرأته وهي ترضع
Narrated by Muslim, Book of Marriage, chapter on the permissibility of ghaylah, which is having intercourse with a nursing woman, and the disapproval of coitus interruptus, no. 1442, from the hadith of Malik through this same chain. It is also found in the Muwatta (Yahya's version), 2/607, 608.