Islam permits slavery but I haven't been able to find anything regarding keeping slaves who are Muslims.
Considering a hypothetical scenario taking place during the early Islamic days where one Muslim nation goes to war with another Muslim nation and one of them comes out victorious. What would the ruling be in context of Islamic Doctrine regarding taking war booty and slaves from the fallen Muslim nation?
Are there any ruling at all in Quran or Hadith?
Thank you.
Well it's haraam for Muslims to fight each other and take each others properties.
But besides the scenario, it's permitted to have Muslim/Mumin slaves. Allah speaks about believing slaves in several ayahs of the Quran.
In Surah al-Baqara 2:221 =
And do not marry polytheistic women until they believe. And a believing slave woman is better than a polytheist, even though she might please you. And do not marry polytheistic men [to your women] until they believe. And a believing slave is better than a polytheist, even though he might please you. Those invite [you] to the Fire, but Allah invites to Paradise and to forgiveness, by His permission. And He makes clear His verses to the people that perhaps they may remember.
Surah an-Nisa 4:92 =
And never is it for a believer to kill a believer except by mistake. And whoever kills a believer by mistake - then the freeing of a believing slave and a compensation payment presented to the deceased's family [is required] unless they give [up their right as] charity...
So Allah speaks about believing slaves while they are enslaved. There's nothing wrong with having slaves in general as long as you treat them properly and give them their rights.
As enslave means: To make someone (a free person) his slave: the answer is no.
Abu Hurairah (May Allah be pleased with him) reported:
The Prophet (ﷺ) said, "Allah, the Exalted, says: 'I will contend on the Day of Resurrection against three (types of) people: One who makes a covenant in My Name and then breaks it; one who sells a free man as a slave and devours his price; and one who hires a workman and having taken full work from him, does not pay him his wages."'
[Sahih al-Bukhari] Supposing slavery still exists or is considered to be allowed nowadays:
Muslims are prohibited to enslave Muslims! And they shouldn't "make" Muslim slaves. As even in a war between Muslims war prisoners are not allowed!
But if a slave converts while being in possession of a Muslim this is allowed (However, as you may read in Sahih Muslim, where a war prisoner declared to the prophet he was a Muslim and the prophet didn't accept his "Islam conversion" after he was captured and used him to ransom Muslim prisoners of war on the enemy side) and this is among the kinds of slavery which is mentioned when Allah speaks about believing slaves in Quran (Maybe we can also add to them those of the people of the book) beside this there's the case of by enemies "enslaved Muslims" after a lost battle of which freeing is by paying the ransom is a good deed. And the Muslim master will still have all the rights (and duties) on his slave. As slavery could also be a way of invitation to Islam!
A Muslim can own a Muslim slave. There are verses in the Quran which mention Muslim (believing) slaves such as 4:25 and 4:92 and 2:221. Muslim slaves can exist by the following means:
A disbeliever who was captured or enslaved first and later converted to Islam remains a slave
A child of a Muslim slave woman through marriage with other than its owner, is a slave.
A Muslim can not enslave another Muslim, meaning that if a Muslim already has the status of a free person under Islamic law then that status is perpetual - the person would always remain free and can never be enslaved.
The evidence of that includes:
The hadith:
قال الله ثلاثة أنا خصمهم يوم القيامة... ورجل باع حرا فأكل ثمنه
Allah says, 'I will be against three persons on the Day of Resurrection: ... One who sells a free person (as a slave) and eats the price ... '
— Bukhari
This is a condemnation and hence a prohibition of the sale of a free person.
Note that حر (free) is a general category which includes a free Muslim by default. A Harbi non-Muslim is an excluded from it because of other evidence such as the enslavement of Banu Quraiza, Banu Mustaliq, Banu Fazara the captives of Khyber, Awtas etc. However there is no evidence to exclude a free Muslim from this prohibition hence it is forbidden to sell a free Muslim according to this hadith. When one text is general and the other is specific then they are combined to arrive at a ruling which satisfies both.
Also note that while the hadith forbids sale any alternate benefit derived would also be forbidden by analogy. For example if one enslaves a free Muslim but utilizes him as a personal servant rather than selling him then this too is forbidden as it is taking benefit at their expense similar to sale. This is also corroborated by the hadith:
ثلاثة لا تقبل لهم صلاة ... ومن اعتبد محررا
There are three whose prayer are not accepted: ... and one who enslaves a freed person.
Also note that sale, including the sale of a slave is permissible and so is consuming the price earned from a sale. Hence the root of the prohibition is that it is the sale of a 'free' person i.e. enslavement.
The ahadith:
كل المسلم على المسلم حرام ماله وعرضه ودمه
Everything of a Muslim is sacred to a Muslim : his property, honour and blood.
أمرت أن أقاتل الناس حتى يشهدوا أن لا إله إلا الله وأن محمدا رسول الله ... فإذا فعلوا ذلك عصموا مني دماءهم وأموالهم إلا بحق الإسلام
I have been ordered (by Allah) to fight against the people until they testify that none has the right to be worshiped but Allah and that Muhammad is Allah's Messenger ... so if they perform that, then they save their lives and property from me except for Islamic laws
— Bukhari
This proves that everything of a Muslim including life, property and honor is by default sacred and hence can not be taken without a legal right. Freedom is a part of everything. Further freedom is inclusive of and more important than property since after enslavement a person can not own any property in reality and whatever he has comes under the ownership of and and can be taken by his owner.
ضرب الله مثلا عبدا مملوكا لا يقدر على شيء ومن رزقناه منا رزقا حسنا فهو ينفق منه سرا وجهرا هل يستوون الحمد لله بل أكثرهم لا يعلمون
Allah presents an example: a slave [who is] owned and unable to do a thing and he to whom We have provided from Us good provision, so he spends from it secretly and publicly. Can they be equal? Praise to Allah! But most of them do not know.
ومن ابتاع عبدا فماله للذي باعه إلا أن يشترط المبتاع
He who buys a slave, his property belongs to one who sells him except when a provision has been laid down by the buyer (that it will be transferred to him with the slave).
— Bukhari
The hadith and Ijma' regarding the treatment of armed Muslim rebels:
قال رسول الله - صلى الله عليه وسلم - هل تدري يا ابن أم عبد, كيف حكم الله فيمن بغى من هذه الأمة , قال: الله ورسوله أعلم. قال: لا يجهز على جريحها, ولا يقتل أسيرها, ولا يطلب هاربها, ولا يقسم فيؤها
The Messenger of Allah (ﷺ) said “Do you realize Ibn Umm ’Abd what the ruling of Allah is concerning those who rebel against the ruler in this Ummah?’ I said, ‘Allah and His Messenger know best.
He said: "A wounded man among them is not to be given the last stroke (that kills him), their captive is not killed, the one who runs away is not followed and their booties are not divided (among other Muslims)."
وقد اتفق الفقهاء على عدم جواز سبي نساء البغاة وذراريهم ... ويتفق الفقهاء على عدم استرقاق أسرى البغاة
The jurists are agreed that it is forbidden to enslave the women and children of rebels ... And the jurists are agreed that it is forbidden to enslave rebel prisoners
The state of war against disbelievers and the resulting booty is the means of enslavement in Islam. This proves that the same does not extend to wars between Muslims themselves.
The ahadith and Ijma' on a harbi disbeliever who accepts Islam:
قال إني مسلم . قال لو قلتها وأنت تملك أمرك أفلحت كل الفلاح
The prisoner said: "I am a Muslim",
Whereupon the Prophet ﷺ said: "Had you said this when you had been the master of yourself, you would have gained every success."
— Muslim
وإذا لقيت عدوك من المشركين فادعهم إلى ثلاث خصال - أو خلال - فأيتهن ما أجابوك فاقبل منهم وكف عنهم ثم ادعهم إلى الإسلام فإن أجابوك فاقبل منهم وكف عنهم
When you meet your enemies who are polytheists, invite them to three courses of action. If they respond to any one of these, you also accept it and withhold yourself from doing them any harm. Invite them to (accept) Islam; if they respond to you, accept it from them and desist from fighting against them.
— Muslim
أسلم تسلم
If you accept Islam you will be safe
واتفقوا أن الحربي الذي يسلم في أرض الحرب ويخرج الينا مختارا قبل أن يؤسر أنه لا يحل قتله ولا أن يسترق
There is agreement that if a Harbi accepts Islam and comes out to us voluntarily before he is captured then it is not permitted to kill him nor to enslave him
This proves that even if a person from the Dar al-Harb accepts Islam before capture then he is safe and can not be harmed, including the harm of enslavement.
The verse:
وإن كان ذو عسرة فنظرة إلى ميسرة وأن تصدقوا خير لكم إن كنتم تعلمون
And if someone is in hardship, then [let there be] postponement until [a time of] ease. But if you give [from your right as] charity, then it is better for you, if you only knew.
Because this verse abrogates enslavement for the inability to repay a debt, which was one of the sources of enslavement beforehand - see Tafsir al-Qurtubi,
The verse:
والسارق والسارقة فاقطعوا أيديهما جزاء بما كسبا نكالا من الله
[As for] the thief, the male and the female, amputate their hands in recompense for what they committed as a deterrent [punishment] from Allah.
Because this verse abrogates enslavement as a punishment for theft which was one of the sources of slavery beforehand - see Quran 12:74-75 and Tafsir al-Qurtubi.
Hence there isn't any way that a free Muslim can be enslaved, be it due to war or a legal punishment. However if a person was born a Muslim slave or if a slave accepts Islam then he\she remains a slave.
I will however note here the case of a Muslim who leaves Islam. The hadith on apostasy states:
من بدل دينه فاقتلوه
Whoever changes his religion, kill him
— Bukhari
This means that an apostate is to be killed (unless they repent and revert to Islam) and hence can not be enslaved. This is largely agreed upon however there exits a rare opinion that a female apostate can be enslaved as killing disbelieving women is forbidden. However this is not a mainstream view rather most of the Hanafis perpetually imprison a female apostate rather than enslaving her while the majority execute her.
It’s prohibited to enslave other Muslims.
Even if two Muslim nation goes to war the Quran says a third party should resolve the matter and all captive of wars will be freed from the Muslims like the Prophet and his companions did after Juwayriya‘s tribe converted.
Please don't misunderstand slavery in the Islamic context with slavery in the western imperial colonial context. The latter is not allowed in Islam. Exploitation is not allowed in Islam. You cannot take another person's hak (rights) including the hak of non-believers. If you do, that victim person will get his justice from you on the day of judgement. Allah is the best of judges.
The only exceptions are prisoners of war, and prisoners from crimes they committed. There is no prison system in true Islam. There is no record of a prison or detainment center in Mecca or Medina at our prophet's time. If a person committed a crime, either they received swift one time punishment on the spot, or they would agree to compensate the victim by being enslaved for a period of time to the victim or his family, or they would be exiled to a remote land and lose their property. The latter is what happened to certain Jewish tribes in Medina when they rebelled or conspired against the prophet (pbuh).
So to answer your question, if a muslim committed a crime against another muslim, then voluntary servitude of the offender to the victim or victim's family is a just and Islamically sanctioned way to settle the matter.
