A man freed a slave of his by tadbir, meaning the slave would become free upon the man's death, and he had no other property besides him. So the Prophet ﷺ ordered that the slave be sold, and he was sold for seven hundred, or nine hundred.
حدثنا أحمد بن حنبل حدثنا هشيم عن عبد الملك بن أبي سليمان عن عطاء وإسمعيل بن أبي خالد عن سلمة بن كهيل عن عطاء
أن رجلا أعتق غلاما له عن دبر منه ولم يكن له مال غيره فأمر به النبي ﷺ فبيع بسبع مائة أو بتسع مائة
Bukhari, Sales, Chapter: The Sale of a Mudabbar, hadith no. 2230, from the hadith of Ismail bin Abu Khalid, and Muslim, Oaths, Chapter: The Permissibility of Selling a Mudabbar, hadith no. 997, after hadith no. 1668, from the hadith of Ata, through him.