ومن ملك مملوكين صغيرين أحدهما ذو رحم محرم من الآخر لم يفرق بينهما وكذلك إن كان أحدهما كبيرا والآخر صغيرا فإن فرق بينهما كره له ذلك وجاز البيع وإن كانا كبيرين فلا بأس بالتفريق بينهما
Translation: In historical slavery cases, minor close mahram relatives were not to be separated; the same restriction applied if one was young and the other adult. Separation was objectionable yet a sale could take effect; where both were adults, the text does not prohibit separation on this ground.
This is a historical slavery-law passage. It offers no contemporary permission to trade human beings.
Dhu rahim mahram refers to a close kinship where marriage is permanently prohibited, such as parent and child.
The text distinguishes protecting family ties from the technical operation of a historical transaction: separation may be objectionable even where a sale is deemed to take effect.