Muwatta Malik, Book 38, Hadith 7 (USC-MSA) ⓘ
Malik related to me that he had heard that a slave-girl came to Umar ibn al-Khattab (who had been beaten by her master with a red hot iron) and he set her free. Malik said, "The generally agreed- on way of doing things among us is that a man is not permitted to be freed while he has a debt against him which exceeds his property. A boy is not allowed to be set free until he has reached puberty. The young person whose affairs are managed cannot set free in his property, even when he reaches puberty, until he manages his property."
وَحَدَّثَنِي مَالِكٌ، أَنَّهُ بَلَغَهُ أَنَّ عُمَرَ بْنَ الْخَطَّابِ، أَتَتْهُ وَلِيدَةٌ قَدْ ضَرَبَهَا سَيِّدُهَا بِنَارٍ أَوْ أَصَابَهَا بِهَا فَأَعْتَقَهَا . قَالَ مَالِكٌ الأَمْرُ الْمُجْتَمَعُ عَلَيْهِ عِنْدَنَا أَنَّهُ لاَ تَجُوزُ عَتَاقَةُ رَجُلٍ وَعَلَيْهِ دَيْنٌ يُحِيطُ بِمَالِهِ وَأَنَّهُ لاَ تَجُوزُ عَتَاقَةُ الْغُلاَمِ حَتَّى يَحْتَلِمَ أَوْ يَبْلُغَ مَبْلَغَ الْمُحْتَلِمِ وَأَنَّهُ لاَ تَجُوزُ عَتَاقَةُ الْمُوَلَّى عَلَيْهِ فِي مَالِهِ وَإِنْ بَلَغَ الْحُلُمَ حَتَّى يَلِيَ مَالَهُ .
also referenced under: Book 38, Hadith 1472 (In-Book)