All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ʻalayhi wa sallam, is His Slave and Messenger.
The Hadeeth reads: “My community (Ummah) will divide into more than seventy sects, the largest of them being a sect of people who measure matters with their opinions, and so make forbidden what is lawful, and make lawful what is forbidden.”
The Hadeeth scholars held different opinions regarding the authenticity of this Hadeeth with this wording. Some scholars declared it Saheeh (sound), such as Al-Haakim, who commented in his book Al-Mustadrak: “This is an authentic Hadeeth according to the criteria of Al-Bukhari and Muslim although they did not report it.” Ath-Thahabi did not comment on it in his revision of the the Mustadrak.
Al-Haythami declared its chain of transmission authentic in his book Majmaʻ Az-Zawaa’id, saying: “The narrators of this Hadeeth are those found in the authentic literature.”
Al-Muʻaallimi said in At-Tankeel: “This Hadeeth is corroborated by other supportive reports that are traced back to the Prophet or the Companions.”
However, Ibn Maʻeen declared it inauthentic. Al-Khateeb Al-Baghdaadi said in his book Tareekh Baghdaad, “This Hadeeth has no basis.” Al-Bazzaar said in Al-Bahr Az-Zakhkhaar: “Nuaʻaym ibn Hammaad was the only reporter who narrated this Hadeeth and no other supportive report has been transmitted with the same chain of narration (to corroborate it).”
Ibn Hajar said, “Nuaʻaym ibn Hammaad has been labeled as a weak narrator by some Hadeeth scholars who criticized him for narrating such an inauthentic report.” [Mukhtasar Al-Bazzaar]
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Allaah Knows best.