Tafsir of Al-Kahf 18:104

"Those whose effort is lost"—meaning: it is wasted and nullified entirely in the sight of Allah (Almighty and Majestic).

"In the worldly life"—This is linked to "effort," not to "lost," because the invalidation of their effort is not restricted to the worldly life.

It has been said: The intent is the people of the two scriptures (the Jews and the Christians). This has been narrated from Ibn Abbas, Sa’d bin Abi Waqqas, and Mujahid. In this case, the works included are the abrogated rulings related to acts of worship that they performed. Others have said: They are the monks who seclude themselves in hermitages and subject themselves to arduous spiritual exercises. Others have said: They are the Sabians.

Ibn al-Kawwa’ asked Ali (may Allah honor his face) about them, and he replied: "Among them are the people of Harura," meaning the Khawarij. This was found problematic because the words of the Exalted, "Those are the ones who disbelieved..." and so on, reject this, as the Khawarij do not deny the Resurrection and are not (in their own view) disbelievers. The reply to this is that the "among them" (minhum) implies connection, and it is not required that they be connected in every respect; it is sufficient that they share in misguidance. Furthermore, it is permissible that he (may Allah honor his face) believed in their disbelief, and it is viewed as an allusion to them by way of severe rebuke, not as a direct exegesis of the verse.

It is mentioned in Majma’ al-Bayan that al-Ayyashi narrated through his chain of authority that Ibn al-Kawwa’ asked the Commander of the Faithful (may Allah honor his face) about the people of this verse, and he said: "They are the People of the Scripture who disbelieved in their Lord and innovated in their religion, so their works were rendered void; and the people of the River [Nahrawan, i.e., the Khawarij] are not far from them." This supports the first answer and indicates that the intended meaning generalizes to all disbelievers.

The grammatical position of the relative pronoun (al-ladhina) is in the nominative case as the predicate of an omitted subject, as if it were a response to a question—as though it were asked, "Who are they?" and the reply was, "Those who..." etc. It is also permitted that it be in the genitive case as an ‘atf bayan (explanatory apposition) for "the greatest losers." It is also permitted that it be an adjective or a substitute, or in the accusative case due to blame, under the condition that the answer is what follows (if Allah wills) from His saying, "Those are the ones who..." etc.

This has been objected to on the grounds that the beginning of that verse does not signify the loss of works or the straying of effort, as the context of the answer and the subsequent inferential connection demand. Even if the first inferential connection indicates the voiding of their works, it is silent regarding the proclamation of that which is the essence in realizing the meaning of "loss," despite their confidence in the accrual of profit and their belief in the utility of what they produced. Moreover, the second inferential connection essentially cuts off that possibility entirely, as there is no room to include it under the command based on the Nun of Majesty (the "We" in the Quran), and the answer to that cannot be completed except through artificial construction. So, contemplate this.

"And they think that they are doing good work"—"Doing good" (al-ihsan) is performing works in the appropriate manner, which is their descriptive goodness that entails their inherent goodness. That is, they believe that they are performing these acts in the appropriate manner due to their being impressed with the works they strove to establish and labored to acquire.

The sentence is a state (hal) from the actor in "strayed," meaning: their mentioned effort strayed while they were thinking that they were doing good in that and would benefit from its effects. Or, it is a state from the possessor of the pronoun in "their effort" (sa’yihim) because it is in the nominative position, meaning: their effort was invalidated while they were, etc.

The difference between the two views is that in the first, the state accompanying their mentioned calculation is the straying of their effort, while in the second, it is the effort itself. It has been said that the first is more profound in clarifying their error. It is not hidden that between yahsabuna (they think) and yuhsinuna (they do good) there is a tajnis al-tashif (a form of paronomasia where words share similar letter shapes). Similar to this is the statement of al-Buhturi: He who is deceived by Allah during the night would not be helpless, And he who is honored by Allah [the Mu‘tazz] would not be a seeker [of others].