مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2914
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn ‘Abbas (رضي الله عنه) said: The Messenger of Allah said: Whoever has intercourse with his female slave and she bears him a child, she becomes free after he dies.”
Musnad Ahmad 2937Hasan; this is a da’eef isnad]