(1) Muhammad ibn Surah ibn Musa ibn al-Dahhak al-Sulami, Abu Isa, better known as al-Tirmidhi al-Dharir (“the Blind”), was one of the foremost hadith authorities of his age. Born in 209 AH/824 CE, he was held up as a model of prodigious memory; leading scholars of his generation and those after them testified to his precision and extensive mastery of hadith and its sciences. He authored the Sunan of al-Tirmidhi, also called al-Jamiʿ al-Sahih, one of the six canonical collections unanimously accepted by Sunni Muslims. He died in 279 AH/892-93 CE. See: al-Bidayah wa-l-Nihayah 11:66; al-Zirikli, al-Aʿlam 6:322. (2) Copy D reads maqwulan (“reported”), which is unlikely; the correct reading is mufassar (“explicitly stated”), as found in al-Tirmidhi. (3) Al-Tirmidhi says: “We do not know it mithla hadha (‘such as this’) except through this route,” i.e., with the added phrase “such as this.” (4) Recorded by al-Tirmidhi, Book of Faith, chapter “On the splitting of this community,” no. 2641 (5/25-26). Al-Hakim also transmitted it with essentially the same wording in al-Mustadrak, Book of Knowledge (1/128-29); the chain is identical, and the verbal differences are minor. The narrator ʿAbd al-Rahman ibn Ziyad is weak. (5) The Companion meant is Saʿd ibn Malik ibn Uhayb ibn ʿAbd Manaf al-Qurashi al-Zuhri, one of the earliest Muslims, one of the ten promised Paradise, a noted cavalryman, the first to shoot an arrow in the path of Allah, and one of the six members of the consultative council appointed by ʿUmar. He commanded major conquests under the Rightly Guided Caliphs, served as governor of Kufa in ʿUmar’s time, was known for having his prayers answered, and kept aloof from the civil strife. He died in 56 AH/676 CE. See: al-Isabah 2:33-34, no. 3194. (6) Copy A has “ʿUmar ibn ʿAwf,” but the correct name is ʿAmr ibn ʿAwf. (7) The word hadith is missing from copy Ṭ. (8) The word dhikr (“mention”) has dropped out of the printed edition.