There are numerous hadiths that tell us the Prophet Muhammad PBUH stoned a number of married adulterers. The most important hadith might be one where the Jews of Medina bring a cause of married adultery before the Prophet PBUH. The Prophet PBUH wants to deal with the adulterers according to Jewish law (probably because no Quranic verse had been revealed regarding the issue). The Jews try to ward off the punishment by saying there is nothing in the Torah about stoning adulterers. But Abdullah b. Salam, a Jewish scholar who converted to Islam, forces them to tell the truth:
Malik related to me from Nafi that Abdullah ibn Umar said, "The Jews came to the Messenger of Allah, may Allah bless him and grant him peace, and mentioned to him that a man and woman from among them had committed adultery. The Messenger of Allah, may Allah bless him and grant him peace, asked them, 'What do you find in the Torah about stoning?' They said, 'We make their wrong action known and flog them.' Abdullah ibn Salam said, 'You have lied! It has stoning for it, so bring the Torah.' They spread it out and one of them placed his hand over the ayat of stoning. Then he read what was before it and what was after it. Abdullah ibn Salam told him to lift his hand. He lifted his hand and there was the ayat of stoning. They said, 'He has spoken the truth, Muhammad. The ayat of stoning is in it.' So the Messenger of Allah, may Allah bless him and grant him peace, gave the order and they were stoned.
Muwatta Book 41, Hadith 1. Also in al-Bukhari, Muslim and others.
The fact that the Prophet PBUH ordered the stoning of some adulterers is uncontroversial. But the most important thing we need to know is whether he ever ordered stoning after Surat al-Nur was revealed, the chapter of the Quran where the issue of adultery is dealt with in some detail. The Quran does not mention stoning of adulterers anywhere, and if we only had the Quran to follow, it would have been clear that adulterers are only to be punished with flogging rather than stoning.
The great 20th century scholar of Islamic law Muhammad Abu Zahra found stoning so repulsive that he considered it impossible that Prophet Muhammad PBUH, sent as a “mercy to mankind”, would instate such a barbaric punishment in his law. (See my essay about his view).
To clarify the matter, I decided to collect all hadiths that mention stoning happening after the Islamic law on the issue was revealed in Surat al-Nur. As it happens, the strongest hadith we have actually tells us that a Companion was unsure whether stoning ever took place after Surat al-Nur was revealed.
Hadith 1
Narrated Ash-Shaibani:
I asked Abdullah bin Abi Aufa about the Rajam (stoning somebody to death for committing illegal sexual intercourse). He replied, "The Prophet (ﷺ) carried out the penalty of Rajam," I asked, "Was that before or after the revelation of Surat-an-Nur?" He replied, "I do not know."
Sahih al-Bukhari 6840, also in Muslim and Mustakhraj Abi Uwana.
Below is a diagram of the chains of this hadith:
This hadith receives an authenticity score of 30.2%, which makes it authentic according to probabilistic hadith verification (which has much more stringent criteria compared to the criteria used by al-Bukhari and other scholars, see my essay about it).
Hadith 2
The following hadith is the strongest hadith we have that states that stoning was carried out after the revelation of Surat al-Nur. In it Umar b. al-Khattab (may God be pleased with him) defends stoning.
Narrated Ibn `Abbas:
Umar said, "I am afraid that after a long time has passed, people may say, "We do not find the Verses of the Rajam (stoning to death) in the Holy Book," and consequently they may go astray by leaving an obligation that Allah has revealed. Lo! I confirm that the penalty of Rajam be inflicted on him who commits illegal sexual intercourse, if he is already married and the crime is proved by witnesses or pregnancy or confession." Sufyan added, "I have memorized this narration in this way."Umar added, "Surely Allah's Messenger (ﷺ) carried out the penalty of Rajam, and so did we after him."
Sahih al-Bukhari 6829, also in Muslim, Ibn Maja, al-Humaydi, Abu Uwana, Musnad Ahmad, Ibn Hibban, Musannaf of Abd al-Razzaq and al-Nasa'i.
Below is the hadith’s chain diagram:
This hadith receives an authenticity score of 27.79%, below the 30% needed for judging it authentic.
Hadith 3
The following is the second and last hadith we have that states stoning was carried out after Surat al-Nur:
Narrated Ash-Sha`bi:
From Ali when the latter stoned a lady to death on a Friday. Ali said, "I have stoned her according to the tradition of Allah's Messenger (ﷺ)."
Sahih al-Bukhari 6812
Below is the hadith’s chain diagram:
This hadith’s fatal weakness is that al-Shaʿbī, according to the hadith scholars al-Ḥākim, Ibn al-Jawzī and Ibn Ḥazm, never heard anything from Ali, therefore there is at least one hidden transmitter before al-Shaʿbī. This makes the hadith receive an authenticity score of 11.08%, making it rather weak, since unknown transmitters are given half the authenticity score of known transmitters in the probabilistic method. But even if we assume the unknown transmitter is entirely trustworthy, the hadith’s score only increases to 22.16%, still below the needed 30%.
Putting Islamic law’s fate in the hands of two men
All of the chains of Hadith 2 above come to us through a single transmitter, Ubaydullah b. Abdullah (it has an alternative chain that is so weak as to be unworthy of consideration). As for Hadith 3, it too comes to us through a single, unknown transmitter.
What this means is that in order to decide whether Islamic law requires the stoning of married adulterers or not, we have to place our entire trust in two men, one of whom is unknown. The law of the Quran (which does not include stoning) has to be ignored because two men tell us, through relatively low-quality hadiths, that stoning took place after Surat al-Nur.
I believe we should require evidence that receives an authenticity score of at least 60% before we can consider anything controversial to be proven beyond doubt. Putting the fate of Islamic law in the hands of two men, and ignoring the Quran for their sake, seems extremely irresponsible to me.
Another piece of evidence in favor of stoning adulterers is Maliki law, which is not entirely derived from hadith, but also from the practice of the people of Medina at the time of Imam Malik (ʿamal ahl al-madīna, or ʿamal for short, which Shaykh Umar Faruq Adullah translates as “Medinan praxis”). But this can be explained as follows: Perhaps after Surat al-Nur was revealed, there were no more cases of adultery brought before the Prophet PBUH. And after he died, since people only remembered the cases where he had stoned adulterers, people assumed this was the right thing to do in such cases. The issue never received much analysis because of the extreme rarity of adultery cases. Islam requires four witnesses to the act, which makes it almost practically impossible to prove a case of adultery. People only remembered the fact that the Prophet PBUH stoned some adulterers, without worrying about whether these cases took place before or after Surat al-Nur. And since there were no cases of adultery judged according to Surat al-Nur in the present or the past, and since all cases of adultery before had been judged according to Jewish law, it was Jewish law that was accepted as the tradition of the Prophet PBUH.
Since stoning is a matter of life and death, and since the Quran’s various verses on the punishment of adulterers contradicts it (slave-women get “half” the punishment of free women in the Quran. How can stoning to death be halved?), I believe we are well-justified in considering stoning an unproven punishment, and well-justified in only carrying out the Quranic punishment.
It may be prudent to add that I believe Islamic law should only be applied when people freely choose to live under it. The question of forcing Sharia law on people should never arise among civilized Muslims.