Hadith 511340
Chapter 28: Marriage - كتاب النكاح
حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، أَنَّهُ قَالَ الْمُحْصَنَاتُ مِنَ النِّسَاءِ هُنَّ أُولاَتُ الأَزْوَاجِ وَيَرْجِعُ ذَلِكَ إِلَى أَنَّ اللَّهَ حَرَّمَ الزِّنَا .
Yahya related to me from Malik from Ibn Shihab that Said ibn al- Musayyab said, "The muhsanat among women are those who have husbands." That referred to the fact that Allah has made fornication haram.
Reference Muwatta Malik 511340
USC-MSA web (English) reference : Book 28, Hadith 39