It is narrated from Sayyiduna Ali (may Allah be pleased with him) that he delivered a sermon and said: "O people, establish the prescribed punishments upon your slaves and slave-girls, whether they are married or unmarried, for a slave-girl of the Messenger of Allah (peace and blessings be upon him) committed fornication, and the Messenger of Allah (peace and blessings be upon him) ordered me to flog her. I went to her and found that she had only recently given birth (and was in post-natal bleeding, nifas). I feared that if I flogged her, she might die. I came to the Messenger of Allah (peace and blessings be upon him) and mentioned this to him, and he (peace and blessings be upon him) said: 'You did well.'" This hadith is sahih on the condition of Imam Muslim, but the two Shaykhs (Bukhari and Muslim) did not record it.