Ibn ‘Abbas reported the Prophet as saying, “When a man’s slave-woman bears him a child she becomes free at his death.”* Darimi transmitted it. * The text has 'au durbur in minhu au ba'dahu’ indicating a doubt on the part of a transmitter as to which words were used. Both expressions amount to the same thing so it seems sufficient to give "at his death" in the translation above.
Hadith Referenceمشكوة المصابيح / كتاب العتق / 3394
Hadith Gradingالألبانی:لم تتمّ دراسته | زبیر علی زئی:إسناده ضعيف
Hadith Takhrij´تحقيق و تخريج: محدث العصر حافظ زبير على زئي رحمه الله` «إسناده ضعيف، رواه الدارمي (257/2 ح 2577) [و ابن ماجه (2515) ] ٭ فيه حسين بن عبد الله: ضعيف و شريک القاضي مدلس و عنعن .»