Sahih Muslim Book 001, Hadith Number 0005.

Chapter : What is Iman and what are its characteristics.

This hadith is narrated to us on the authority of Muhammad b. 'Abdullah b. Numair, on the authority of Muhammad b. 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.