Hadith 10:32
‘Amr b. Shu'aib, on his father’s authority, told that his grandfather reported the Prophet as saying, “When one of you marries his slave to his slave girl he must not look at her private parts.” A version has, “he must not look at what is below the navel and above the knee.” Abu Dawud transmitted it.
وَعَنْ عَمْرِو بْنِ شُعَيْبٍ عَنْ أَبِيهِ عَنْ جَدِّهِ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «إِذَا زَوَّجَ أَحَدُكُمْ عَبْدَهُ أَمَتَهُ فَلَا يَنْظُرَنَّ إِلَى عَوْرَتِهَا» . وَفِي رِوَايَةٍ: «فَلَا يَنْظُرَنَّ إِلَى مَا دُونُ السُّرَّةِ وَفَوْقَ الرُّكْبَةِ» . رَوَاهُ أَبُو دَاوُد
Original Reference: Mishkat al-Masabih 3111