Ibrahim (may Allah have mercy on him) said: The children of a mudabbarah and of an umm walad have the same status as their mothers.
(b) Umar bin Abd al-Aziz (may Allah have mercy on him) said, (concerning) a man who married his umm walad to a slave and she had children: they have the same status as their mother.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب عتق أمهات الأولاد / 21802