´It was narrated from Ibn`Abbas that the Messenger of Allah (ﷺ) said:` “Any man whose slave won an bears him a child, she will be free after he dies.”
Related hadith on this topic
Explanation & Benefits
Shaykh Safi ur-Rahman Mubarakpuri
Takhrij:
«أخرجه ابن ماجه، العتق، باب أمهات الأولاد، حديث:2515، والحاكم:2 /19 وصححه، فتعقبه الذهبي بقوله: "حسين بن عبدالله متروك" وتلميذه عنعن.»©Explanation:
The aforementioned narration is weak in its chain of transmission; however, based on other evidences, the preferred and correct opinion appears to be that an umm walad becomes free automatically after the death of her master.
And Allah knows best.
Source: Bulugh al-Maram: Commentary by Safiur Rahman Mubarakpuri, Page: 1234