Hadith 1

Muwatta Malik

Book 39: The Mukatab
Book 39, Hadith 1
حَدَّثَنِي مَالِكٌ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يَقُولُ الْمُكَاتَبُ عَبْدٌ مَا بَقِيَ عَلَيْهِ مِنْ كِتَابَتِهِ شَىْءٌ ‏.‏
Malik related to me from Nafi that Abdullah ibn Umar said, "A mukatab is a slave as long as any of his kitaba remains to be paid."