مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2889
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn 'Abbas (رضي الله عنه) that: The Prophet (ﷺ) said: "Any woman who gives birth to her master's child becomes free after he dies” or "after he is gone.” Or he may have said both.
Musnad Ahmad 2910Hasan; this is a da'eef isnad]