Majmu' al-Fatawa - Ibn Taimiya - (29/222)

He answered:

If he neither saw the goods nor had them described to him, the sale is invalid, and he must make restitution with their equivalent or their value.

He—may Allah have mercy on him—was asked:

A man with a family to support wishes to sell himself. Is that permissible?

He answered:

Praise be to Allah. As for a sale recognized by Islamic law, a free Muslim cannot be sold. However, he may attach himself to a king or emir, calling himself that ruler’s slave, while the king or emir counts him among his slaves whom he emancipates, without acquiring ownership of him as an actual slave. This resembles the original master’s ownership.

What these people practise is merely a sale according to custom, with the terminology likewise governed by custom. Most mamluks belong to the public treasury, and their bond of patronage is with the Muslims. However, they are attributed to whoever gains power, just as funds and similar things are attributed to him.

There is nothing wrong with a person attaching himself to someone who gives him his due from the Muslims’ public treasury, just as he was previously attached to someone else. They must obey whoever Allah has placed in authority over them in matters consistent with obedience to Allah, but must not obey anyone in disobedience to Allah. Thus, one form of ownership resembles another. And Allah knows best.

فَأَجَابَ: إذَا لَمْ يَرَ الْمَبِيعَ وَلَمْ يُوصَفْ لَهُ: فَالْبَيْعُ بَاطِلٌ وَعَلَيْهِ رَدُّهُ بِمِثْلِهِ أَوْ قِيمَتِهِ. وَسُئِلَ - رَحِمَهُ اللَّهُ -: عَنْ رَجُلٍ يُرِيدُ أَنْ يَبِيعَ رُوحَهُ؟ وَلَهُ عَائِلَةٌ. هَلْ يَجُوزُ ذَلِكَ؟ فَأَجَابَ: الْحَمْدُ لِلَّهِ، أَمَّا الْبَيْعُ الشَّرْعِيُّ: فَالْحُرُّ الْمُسْلِمُ لَا يُمْكِنُ بَيْعُهُ وَلَكِنْ إذَا انْضَمَّ إلَى بَعْضِ الْمُلُوكِ أَوْ الْأُمَرَاءِ مُتَسَمِّيًا بِاسْمِ مَمْلُوكِهِ وَذَلِكَ الْمَلِكُ أَوْ الْأَمِيرُ يَجْعَلُهُ مِنْ مَمَالِيكِهِ الَّذِينَ يُعْتِقُهُمْ لَا يَتَمَلَّكُهُ تَمَلُّكَ الْأَرِقَّاءِ فَهَذَا شِبْهُ مِلْكِ السَّيِّدِ الْأَوَّلِ. وَهَذَا الَّذِي يَفْعَلُهُ هَؤُلَاءِ إنَّمَا هُوَ بَيْعٌ عَادِيٌّ وَإِطْلَاقٌ عَادِيٌّ إذْ أَكْثَرُ الْمَمَالِيكِ مِلْكٌ لِبَيْتِ الْمَالِ وَوَلَاؤُهُمْ لِلْمُسْلِمِينَ؛ وَلَكِنَّ مَنْ غَلَبَ أُضِيفُوا إلَيْهِ كَمَا تُضَافُ إلَيْهِ الْأَمْوَالُ وَنَحْوُ ذَلِكَ وَلَا بَأْسَ عَلَى الْإِنْسَانِ أَنْ يَنْضَافَ إلَى مَنْ يُعْطِيهِ حَقَّهُ مِنْ بَيْتِ مَالِ الْمُسْلِمِينَ كَمَا أُضِيفَ إلَى غَيْرِهِ وَعَلَيْهِمْ أَنْ يُطِيعُوا مَنْ وَلَّاهُ اللَّهُ أَمْرَهُمْ فِي طَاعَةِ اللَّهِ وَلَا يُطِيعُوا أَحَدًا فِي مَعْصِيَةِ اللَّهِ فَالْمِلْكُ يُشْبِهُ الْمِلْكَ وَاَللَّهُ أَعْلَمُ.