Musannaf Ibn Abi Shaybah

It is narrated from Ibn Abi Mulaykah that a woman (slave) was given a contract of manumission (kitabah). Then, during the period of kitabah, she gave birth to two children. Later, she passed away. Regarding this, Abdullah bin Zubair (may Allah be pleased with him) was asked. He said: If her children wish to remain on their mother’s contract of kitabah, then they are permitted; when they pay (the agreed amount), they will become free.