on his father's authority, told that his grandfather reported the Prophet ﷺ said: A slave who has entered into an agreement to purchase his freedom is a slave as long as a dirham of the agreed price remains to be paid. (Using translation from Abū Dāʾūd 3926)
عَنِ النَّبِيِّ ﷺ قَالَ الْمُكَاتَبُ عَبْدٌ مَا بَقِيَ عَلَيْهِ مِنْ مُكَاتَبَتِهِ دِرْهَمٌ