Tafsir of Ya seen 36:49

"They do not await"—this is a response from His side, the Exalted, meaning: They do not expect—"except a single blast." This is a mighty blast, namely the first blowing of the Trumpet, by which the inhabitants of the earth shall die. It is referred to as "awaiting" in consideration of the outward sense of their saying, "When will this promise come to pass?" or because, since the blast must inevitably occur, it is as if they are awaiting it.

"[It] will seize them"—meaning it will overpower them and overtake them, such that they perish—"while they are disputing." That is, they are arguing and contending in their transactions and their trades, with nothing of its dread crossing their minds. This is like the words of the Exalted, "Or the Hour will come upon them suddenly while they are unaware." Thus, they should not be deceived by the absence of its signs according to their own desires, nor should they assume it will not come.

Ibn Jarir and Ibn Abi Hatim recorded from Ibn ‘Umar that he said: "The Trumpet will be blown while people are in their paths, their marketplaces, and their gatherings. Two men may have a garment between them, bargaining over it; one of them will not have released it from his hand before the Trumpet is blown, and he will fall unconscious. This is what Allah, the Exalted, meant by, 'They do not await except a single blast,' and so on."

The two Sheikhs [Al-Bukhari and Muslim] and others recorded from Abu Huraira that the Messenger of Allah, may Allah bless him and grant him peace, said: "The Hour will be established while two men have spread their garment between them; they will not have completed the sale, nor will they have folded it. The Hour will be established while a man is plastering his trough, but he will not drink from it. The Hour will be established while a man has returned with the milk of his ewe, but he will not taste it. And the Hour will be established while a man has raised a morsel to his mouth, but he will not eat it."

The root of yakhiṣimūn (they are disputing) is yakhtaṣimūn (they are arguing). Ubayy recited it this way, where the 'tā' was made quiescent and assimilated into the 'ṣād' after converting it into a 'ṣād', then the 'khā'' was vocalized with a kasra due to the meeting of two quiescent letters. It is also permitted that the kasra is to follow the vowel of the second 'ṣād', and a quiescent letter does not harm as a separator.

The two Haramis, Abu ‘Amr, Al-A‘raj, Shibl, and Ibn Qustantin recited it by assimilating the 'tā' into the 'ṣād' and transferring its vowel—which is a fatha—to the 'khā''. Abu ‘Amr and Qālūn also narrated, with variance, the vocalization of the 'khā'' and the shadda on the 'ṣād'. Another narration from them is the quiescence of the 'khā'' and the light (non-shaddah) 'ṣād', from khaṣamahu (he argued with him). The object in this reading is omitted, meaning: they are disputing with one another. It is also said that yakhiṣimūn refers to their arguing in their own defense. Some vocalize the 'yā'' of the imperfect tense with a kasra to follow the kasra of the 'khā'', with a shadda on the 'ṣād'. Vocalizing the 'yā'' of the imperfect with a kasra is a dialect reported by Sibawayh from Al-Khalil in certain instances.

It is reported from Nafi‘ that he recited it with the 'yā'' having a fatha, the 'khā'' being quiescent, and the 'ṣād' having a kasra and a shadda. This involves combining two quiescent letters by omitting the known [rule], as if it were permitted to combine them if the second is assimilated, whether the first is a lengthening letter or not. This is what we have chosen in transmitting the recitations, following some of the eminent scholars, though the narrators differ in that regard.