"Metaphysical certainty is not God, though it contains something of Him. This is why Sufis accompany even their certainties with this formula: “And God is more wise” (wa ʾLlahu aʿlam). The cult of intelligence and mental passion distances man from truth: intelligence narrows as soon as man puts his trust in it alone; mental passion chases away intellectual intuition just as the wind blows out the light of a candle.Monomania of the mind, with the unconscious pretension, prejudice, insatiability, and haste that are its concomitants, is incompatible with sanctity; indeed sanctity introduces into the flux of thought an element of humility and charity, hence of calm and generosity; far from interfering with the spiritual momentum or the sometimes violent force of truth, this element delivers the mind from the vexations of passions, guaranteeing both the integrity of thought and the purity of inspiration.
According to the Sufis mental passion must be ranked as one of the associations with Satan, like other forms of passional “idolatry”; it cannot directly have God for its object; if God were its direct object, it would lose its specifically negative characteristics. Furthermore it does not contain within itself any principle of repose, for it excludes all consciousness of its own destitution."
--Frithjof Schuon (Spiritual Perspectives and Human Facts)
"Differences arose among the people of a single religion over beliefs and doctrines due to differences in place, language, and the climate of their countries, and also because of the different views held by their leaders, teachers, and scholars who were interested in prestige in this world. There
is a saying, “Be different and you’ll be known.” If the leading scholars
did not disagree among themselves, they would not be able to assert their prestige over one another. Similarly, experts at debate and disputation
invent many things about religion, things the messenger of Allah did not
bring. They make things up, telling people, “This is the precedent set by the messenger.” They make it sound nice and eventually even believe that
what they have made up is true."
-Brethen of Purity (Ikhwan al-Safa')