عَنْ أُمِّ سَلَمَةَ رَضِيَ اللَّهُ عَنْهَا ذَكَرَتْ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ إِذَا كَانَ لِإِحْدَاكُنَّ مُكَاتَبٌ فَكَانَ عِنْدَهُ مَا يُؤَدِّي فَلْتَحْتَجِبْ مِنْهُ
It is narrated from Sayyida Umm Salama (may Allah be pleased with her) that the Noble Prophet (peace and blessings be upon him and his family) said: When any woman among you has a mukatab (contracted for freedom) slave, and he possesses enough wealth to pay his price, then that woman should observe veil from that slave.