Muwatta Malik, Book 54, Hadith 1808 (In-Book)

Malik related to me from his paternal uncle, Abu Suhayl ibn Malik, that his father heard Uthman ibn Affan say in a khutba, "Do not oblige the slave-girl to earn money unless she has a skill. When you oblige her to do that, she will earn money by prostitution. Do not oblige the child to earn money. If he does not find it, he will steal. Have integrity since Allah has integrity with you, and you must feed them good food."

وَحَدَّثَنِي مَالِكٌ، عَنْ عَمِّهِ أَبِي سُهَيْلِ بْنِ مَالِكٍ، عَنْ أَبِيهِ، أَنَّهُ سَمِعَ عُثْمَانَ بْنَ عَفَّانَ، وَهُوَ يَخْطُبُ وَهُوَ يَقُولُ لاَ تُكَلِّفُوا الأَمَةَ غَيْرَ ذَاتِ الصَّنْعَةِ الْكَسْبَ فَإِنَّكُمْ مَتَى كَلَّفْتُمُوهَا ذَلِكَ كَسَبَتْ بِفَرْجِهَا وَلاَ تُكَلِّفُوا الصَّغِيرَ الْكَسْبَ فَإِنَّهُ إِذَا لَمْ يَجِدْ سَرَقَ وَعِفُّوا إِذْ أَعَفَّكُمُ اللَّهُ وَعَلَيْكُمْ مِنَ الْمَطَاعِمِ بِمَا طَابَ مِنْهَا ‏.‏

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also referenced under: Book 54, Hadith 42 (USC-MSA)