Tafsir of Al-Mursalat 77:32

"It" — meaning the Fire indicated by the discourse (and it is said the pronoun refers to the sparks) — "throws sparks." This [term] is what flies off from the fire, so named due to the belief in the evil (sharr) contained within it. It is a collective noun; its singular is shararah, like darah (a house).

"Like castles" — like large, constructed buildings. The intent is that every spark is of such magnitude. What follows [in the verse] indicates this intended meaning, and it is supported by the recitation of Ibn Abbas and Ibn Miqsam as bishirar (with a kasrah on the shin and an alif between the two ras), for the apparent meaning is that it is the plural of shararah, similar to raqabah and riqab, indicating that the singular [spark] is what is being likened to a castle. Likewise is the recitation of Isa as bishirar (with a fathah on the shin and an alif between the two ras); it has been said that this is the plural of shararah, not a singular [noun].

It has been permitted, regarding the recitation with kasrah, that it could be the plural of sharr (evil), not the comparative adjective, like khiyar being the plural of khayr (good). In that case, it is an adjective standing in place of its modified noun—meaning: "it throws [with] evil people"—but this is contrary to the apparent meaning.

It is said that al-qasr refers to thick wood, the singular of which is qasrah, similar to jamrah and jamr. Others say it refers to pieces of wood about the size of a cubit, or more or less, prepared for winter; its singular is likewise. Thus, the similitude is of one collective group to another collective group, without need for the interpretation mentioned earlier, except that the element of terror in the latter view is less than in the former.

Ibn Abbas, Mujahid, Ibn Jubayr, al-Hasan, and Ibn Miqsam recited it as ka-l-qasar (with a fathah on the qaf), which refers to the bases of palm trees, or, as some say, their trunks; its singular is qasrah, like shajarah and shajar. In the Book of Plants, it is stated that the grain has two husks: the lower one is called qishrah and the upper one is called qasrah, from which is the Almighty’s saying "like castles" (ka-l-qasr), though this is strange.

Ibn Mas’ud recited it as ka-l-qusur (with two dammahs), the plural of qasr, like ruhn and ruhun. In al-Bahr, it is suggested that it is as if it were a derivative of qusur (castles), like najm (star) from nujum (stars); this, however, contradicts the apparent meaning, as such a construct is either necessitated by poetic meter or is rare and irregular.

Ibn Jubayr and al-Hasan also recited it as ka-l-qisar (with a kasrah on the qaf and fathah on the sad), the plural of qasrah (with two fathahs), like halqah (a ring of iron) and huluq, or hajah and huwaj. Some reciters read it as ka-l-qasir (with a fathah on the qaf and kasrah on the sad), with the same meaning as the qasr (castle) in the recitation of the majority.