Hasan (may Allah have mercy on him) said: "Sayyiduna Ali (may Allah be pleased with him) was a courageous man, and if someone committed adultery with a slave woman, he would order stoning."
Hadith Referenceسنن سعید بن منصور / كتاب الطلاق / 3440
Hadith Gradingمحدثین:مرسل
Hadith Takhrij«مرسل، وأخرجه سعيد بن منصور فى «سننه» ترقيم الدرالسلفية برقم:، 2263، والبيهقي فى«سننه الكبير» برقم: 17174، وعبد الرزاق فى «مصنفه» برقم: 13424، والطحاوي فى «شرح معاني الآثار» برقم: 4875»
Brief Explanation
In the chain of narration, "Abu Hurrah" is narrating from Hasan with an 'an' (عن) connection, and Hasan al-Basri's hearing (sama‘) from Sayyiduna Ali is not established; therefore, the narration is weak, even though the text is well-known and supported by other reports. The meaning of this athar is in accordance with the well-established juristic position, i.e., that Sayyiduna Ali radi Allahu anhu held the view of stoning (rajm) for a married adulterer (zani muhsan).
Ibn Hajar has also made it clear: "And it is not established that he heard from Ali" (Tahdhib al-Tahdhib 2/263).