Sahih Muslim Book 9, Hadith Number 3490.

Chapter: It is forbidden to divorce the woman during her menses.

A hadith like this is reported on the same authority (but with this difference that the narrator) ‘Abd al-Rahman b. Aiman (was mentioned) as the freed slave of ‘Urwa (Imam Muslim said: He made a mistake who said that it was ‘Urwa; it was in fact the freed slave of ‘Azza.)