Malik said, "A free man must not marry a slave-girl when he can afford to marry a free-woman, and he should not marry a slave-girl when he cannot afford a free woman unless he fears fornication. That is because Allah, may he be Blessed and Exalted, says in His Book, 'If you are not affluent enough to marry believing women, who are muhsanat, take slave-girls who are believing women that your right hands own.' (Sura 4 ayat 24) He says, 'That is for those of you who fear al-anat.' "
Malik said, "Al-anat is fornication."
Arabic : Book 28, Hadith 1123