Narrated Umm Salamah: That the Messenger of Allah (ﷺ) said: "When one of you (women) has a Mukatab ho has with him what will fulfill (the Kitabah) then observe Hijab from him." This Hadith is Hasan Sahih. And the meaning of this Hadith according to the people of knowledge is that of caution. They say that the Mukatab is not freed, even if he has the amount to pay, until he pays it.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا سَعِيدُ بْنُ عَبْدِ الرَّحْمَنِ الْمَخْزُومِيُّ، قَالَ حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنِ الزُّهْرِيِّ، عَنْ نَبْهَانَ، مَوْلَى أُمِّ سَلَمَةَ عَنْ أُمِّ سَلَمَةَ، قَالَتْ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا كَانَ عِنْدَ مُكَاتَبِ إِحْدَاكُنَّ مَا يُؤَدِّي فَلْتَحْتَجِبْ مِنْهُ " . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ . وَمَعْنَى هَذَا الْحَدِيثِ عِنْدَ أَهْلِ الْعِلْمِ عَلَى التَّوَرُّعِ وَقَالُوا لاَ يُعْتَقُ الْمُكَاتَبُ وَإِنْ كَانَ عِنْدَهُ مَا يُؤَدِّي حَتَّى يُؤَدِّيَ .
sunnah.com