Jami` at-Tirmidhi, Volume 3, Book 12, Hadith 1261 (DarusSalam) ⓘ

Narrated Umm Salamah: That the Messenger of Allah said: "When one of you (women) has a Mukatab ho has with him what will fulfill (the Kitabah) then observe Hijab from him." [Abu 'Eisa said:] 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.

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 ‏.‏