The Prophet ﷺ forbade the earnings of female slaves.
حدثنا حجاج قال حدثنا شعبة قال سمعت محمد بن جحادة يحدث عن أبي حازم
عن النبي ﷺ أنه نهى عن كسب الإماء
No references are available.
Its isnad is sahih. Bukhari, 3/147, in the chapter on sharecropping, in the section titled "one who holds that the owner of the pool or waterskin has more right to its water," transmitted it with wording close to this, as did Ibn Majah, 2/1439, no. 4306.