Maliks Muwatta Book 41, Hadith Number 16A.

Malik related to me from Yahya ibn Said that Sulayman ibn Yasar informed him that Abdullah ibn Abbas ibn Abi Rabia al-Makhzumi said, “Umar ibn al-Khattab gave me orders about the slaves of Quraysh and we flogged some of the slave-girls of the muslim lands fifty times each for fornication.”