This hadith is narrated to us on the authority of Muhammad bin 'Abdullah bin Numair, on the authority of Muhammad bin Bishr, on the authority of Abd Hayyan al-Taymi with the exception that in this narration (instead of the words (Iza Waladat al'amah rabbaha), the words are (Iza Waladat al'amah Ba'laha), i.e, when slave-girl gives birth to her master.