Muhammad: (24) Do they not then reflect on the Quran...

(Do they not then reflect on the Quran?) That is: Do they not observe it, contemplate it, and consider the admonitions and warnings contained within it, so that they might not fall into the ruinous sins they have fallen into?

(Or are there locks upon their hearts?)

This is a metaphor for the inability of the message to reach them or for the truth to be unveiled to them. It is as if it were said: Do they not reflect on the Quran when it reaches their hearts, or has it not reached them at all? Thus, 'am' (or) is connective (muttasilah), according to the school of Sibawayh and the apparent view chosen by some.

Abu Hayyan and a group of others held that it is disjunctive (munqati'ah), carrying the meaning of "nay" (bal), to transition from rebuking them for abandoning reflection to rebuking them for the fact that their hearts are locked—incapable of reflection or contemplation. The interrogative particle (al-hamzah) is for affirmation.

The indefiniteness of "hearts" (qulub) is to emphasize the gravity of their condition and the hideousness of their state regarding hardness and ignorance; as if it were said: "Upon hearts of an unknown nature, whose extent of hardness and ignorance cannot be fathomed." It is also said that it is because the intent is the hearts of some of them—namely, the hypocrites—so the indefiniteness is for specification (partitive) or for categorization, as has been said.

The genitive construction of the "locks" to the hearts is to signify that these are locks peculiar to them, suitable to them, and not of the same nature as ordinary, known locks. It is also read as iqfaliha (with a kasra on the hamzah), which is the verbal noun of af'ala, and as aqfaluha (in the plural form af'ul).