Muwatta Malik, Book 28, Hadith 1133 (In-Book) ⓘ

Yahya related to me from Malik from Ibrahim ibn Abi Abla from Abd al-Malik ibn Marwan that he gave a slave-girl to a friend of his, and later asked him about her. He said, "I intended to give her to my son to do such-and-such with her." Abd al-Malik said, "Marwan was more scrupulous than you. He gave a slave-girl to his son, and then he said, 'Do not go near her, for I have seen her leg uncovered.' "

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ إِبْرَاهِيمَ بْنِ أَبِي عَبْلَةَ، عَنْ عَبْدِ الْمَلِكِ بْنِ مَرْوَانَ، أَنَّهُ وَهَبَ لِصَاحِبٍ لَهُ جَارِيَةً ثُمَّ سَأَلَهُ عَنْهَا فَقَالَ قَدْ هَمَمْتُ أَنْ أَهَبَهَا لاِبْنِي فَيَفْعَلَ بِهَا كَذَا وَكَذَا ‏.‏ فَقَالَ عَبْدُ الْمَلِكِ لَمَرْوَانُ كَانَ أَوْرَعَ مِنْكَ وَهَبَ لاِبْنِهِ جَارِيَةً ثُمَّ قَالَ لاَ تَقْرَبْهَا فَإِنِّي قَدْ رَأَيْتُ سَاقَهَا مُنْكَشِفَةً ‏.‏