The pronoun "they (hum)" infers restriction [to themselves] and [its purpose] is to reject their self-justification and repulse their imputation of fee-ble-mindedness to the believers, indicated by "as the weak-minded believe (ka-mâ âmana al-sufahâ')." That is, the weak-minded are those people who 112
give up [working for] the hereafter at the behest of their pride and self-interest and fleeting pleasures, unlike those who earn eternal life by giving up their ephemeral desires.
The definite article "al" of "al-sufahâ' - [the] weak-minded" indicates that it is a known fact that they are weak-minded. It also denotes completeness; that is, theirs is complete weak-mindedness. "But they know it not (wa lâkin lâ ya'lamûn):" This contains three indications:
The First: Knowledge and insight are necessary to distinguish between truth and falsehood and differentiate between the way of the believers and that of the dissemblers, unlike [the dissemblers'] corruption and dissension, which can be perceived by those of least intelligence. For this reason, [as this verse is concluded with the phrase, "but they know it not"], the previous verse has appended to it the phrase, "but they perceive it not."
The Second: "They do not know," like similar phrases at the ends of verses such as "they do not use their reasons (lâ ya'qilun)," "they do not reflect (lâ yatafakkarûn)," and "they do not recall (lâ yatadhakkarûn)" show that Islam is founded on reason, wisdom, and knowledge. It is characterized by being acceptable by all sound minds, unlike other religions, which are based on blind imitation and bigotry. This indication presages well [for Islam], as is discussed elsewhere.1
The Third: One should avoid [the dissemblers] and not concern oneself with them, for there is nothing to be gained from offering them advice; they are not aware of their ignorance that they might try to dispel it and be quit of it.
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1.This refers to al-Khutba al-Slıâmiyya (Turk. Hutbe-i şamiye) (1911). For English translation, see, The Damascus Sermon (Istanbul: Sözler Publications, 1996), 27-43.