Hanbal say, “No one of Ishaq’s caliber has ever crossed the bridge into Khurasan. Even though he and we disagreed on certain points, people have always differed with one another. (1)
Muhammad ibn Aslam al-Tusi said, when Ishaq passed away, “I know of no one whose fear of Allah was greater than Ishaq’s. Allah—Exalted is He—says: ‘It is only those of His servants who possess knowledge that truly fear Allah.’ (2) [Fatir: 28] He was also the most learned of people. Had Sufyan al-Thawri been alive, he would have needed Ishaq.”
Ahmad ibn Saʿid al-Ribati said, “If al-Thawri and the two Hammads were still alive, they would have turned to Ishaq in many matters.”
Abu Muhammad al-Darimi said, “Ishaq surpassed the scholars of both East and West by virtue of his integrity.”
Muhammad ibn Ishaq al-Sarrāj said, “A man once stood at Ishaq’s grave and recited:
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(1) Such is the way of truly great men: their hearts are expansive, they acknowledge the efforts of others, and they openly celebrate their merits. The divergence of the mujtahid imams in understanding the Quran and the Sunnah is perfectly natural in Islamic law, for most of its texts are probabilistic in meaning. Allah willed and approved this variety; it is a mercy, a source of ease, and an arena for competition and creativity. One of its fruits is the vast literary heritage that now fills Islamic libraries with works of every kind. Their differences regarding the Quran concern only some rulings they inferred from it, and arise from subtleties in its indication—such as polysemy, the specification of a general term, the restriction of an absolute term, the presence of abrogation, and other causes discussed in the appropriate works. As for the Sunnah, disagreement is not confined to interpreting what a hadith means, as with Quranic verses; it also extends to judging the hadith itself—declaring it sound or weak—so that one scholar may deem authentic what another considers unreliable. These and many other causes of disagreement are catalogued by the scholars in their writings. The Quranic verses that condemn disagreement refer only to the blameworthy kind that produces fanaticism, rancour, attacks on an opponent’s honour or faith, and imputations of things for which he is blameless.
(2) Ibn Kathir comments on this verse: “Only those who truly know Allah fear Him as He ought to be feared; for the more complete one’s knowledge of the Almighty, the All-Powerful, the All-Knowing—described by attributes of perfection and beautiful names—the greater and deeper one’s fear of Him.” For further discussion see: Ibn Kathir, Tafsir; al-Baghawi, Tafsir, vol. 7, p. 60.