Tafsir of Al-Kahf 18:43

"And there was no..." (Wa lam takun lahu): The two brothers [Hamzah and Al-Kisa'i], Mujahid, Ibn Wathab, Al-A'mash, Talha, Ayyub, Khalaf, Abu Ubaydah, Ibn Sa'dan, Ibn Isa al-Asbahani, and Ibn Jarir recited it as yakun with a ya' (masculine), because the nominative subject—namely, His saying, "a company" (fi'ah)—is not of a true feminine gender, the verb precedes it, and a separator (the accusative) has been placed between them. In His statement, "they help him" (yansurunahu), the meaning was observed, so the pronoun was brought as a plural to match the meaning.

Ibn Abi Ablah recited, "And there was no (takun) for him a company that helps him," observing only the literal gender of the word.

The intended meaning of "help" (nusrah) is its necessary consequence, which is the ability to provide it. That is, there was no company capable of helping him—either by averting destruction before it occurred, or by restoring the exact destroyed entity (according to the view that permits the restoration of the exact non-existent), or by restoring its equivalent (according to the view that denies the possibility of the former).

"Other than Allah" (min duni Allah): For He, the Glorified and Exalted, is the One capable of helping him alone. Metaphorical speech was employed here, because if the phrase were left to its literal sense, it would imply that Allah Almighty does help him. For when it is said, "No one helps Zayd other than Bakr," it is understood in common usage that Bakr helps him, yet that is not what is intended. Rather, the intended meaning is what you have heard; the conclusion is that they have no power to help him, except for Allah Almighty, the All-Powerful.

"And he was not" (wa ma kana) in himself "a defender" (muntasiran); [he was not] capable by his own strength of preventing Allah Almighty's vengeance upon him.