The Messenger of Allah ﷺ said, "The Quran was revealed in seven modes of recitation."
أن رسول الله ﷺ قال: نزل القرآن على سبعة أحرف.
Ahmad (20179) narrated it from Bahz, who said, Hammad bin Salama narrated to us, Qatada informed us, from Hasan, from Samura, and he related it. Its isnad is sahih.Hasan here is Imam Basri, who practiced tadlis and narrated this using the ambiguous form "from." Scholars differed over whether he heard directly from Samura, and what seems most likely to me is that he heard from him without restriction, as Bukhari and others held.However, Ahmad (20262) narrated it from Affan, who said, Hammad narrated to us, Qatada informed us, from Hasan, from Samura, that the Messenger of Allah ﷺ said, "The Quran was revealed in three forms." Bazzar narrated it through this same route in Kashf Astar (2314), as did Tahawi in Mushkil Athar (3119), Tabarani in Kabir (6853), and Hakim (223/2). Hakim said, "Bukhari relied on Hasan's narration from Samura as evidence, and Muslim relied on the hadiths of Hammad bin Salama as evidence. This hadith is sahih and has no defect."The sahih and widely-transmitted reports establish that the Quran was revealed in seven forms. Tahawi's view in his Mushkil is that Samura may have heard this at a time when the Quran was being recited in only three forms, no more than that, and then he passed away before the report came from the Prophet ﷺ that the Quran was recited in more than that, up to a total of seven forms. So Samura never heard that, and he simply narrated what he had heard.I say, rather, he also heard about the seven forms, as mentioned above, and perhaps this discrepancy goes back to some of the narrators who erred in transmitting from him. It would not be surprising if this error came from Hammad bin Salama, for he narrated the hadith through three different versions. The first version is the sahih one, the second version contains an irregularity, and likewise the third version, which is his statement, "The Quran was presented to the Messenger of Allah ﷺ in three presentations." Bazzar (4564) narrated it from Muhammad bin Muthanna, who said, Hajjaj bin Minhal narrated to us, Hammad bin Salama narrated to us, and he related it.