Al-Mustawrid (may Allah have mercy on him) says that a man came to Ibn Mas'ud (may Allah be pleased with him) and said: My uncle has married me to his slave girl, and he wants to make my children his slaves. Ibn Mas'ud (may Allah be pleased with him) said: That is not his right.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العتق / 21424