Tafsir of Al-Qamar 54:26

(They will know tomorrow who is the insolent liar)

This is a narrative of what Allah, Exalted be He, said to Salih, peace be upon him, as a promise to him and a warning to his people. The 'seen' (in saya‘lamun) serves to bring the meaning of the sentence closer and emphasize it. "Tomorrow" refers to the time when worldly torment descends upon them. It has also been said that it refers to the Day of Resurrection, for it signifies any future time, and it was used to express proximity. An example of this is the saying of al-Tirimmah:

“So entertain me before the wailing of the mourners, And before the agitation of the soul amidst needs, And before ‘tomorrow’—alas for my soul regarding tomorrow, When my companions depart and I do not depart.”

This means: They will certainly know, in the near future, who the insolent liar is—the one whose insolence and arrogance drove him to do what he did: is it Salih, or is it those who called him a liar? The intent is: "They will know that they are the insolent liars." However, it is phrased in a manner of ambiguity, signaling that it is a matter that is scarcely hidden. Similar to this is the poet's saying:

"For if I meet you when we are alone, you shall know (which of the two of us)—you or I—is the knight of the factions."

Ibn Amir, Hamzah, Talha, Ibn Waththab, and al-A‘mash read it as sata‘lamun (you will know) with a ta’ of address, as a report of what Salih said to them in response to them. In al-Kashshaf, it is said that this is speech by way of iltifat (shift in mode of address). The author of al-Kashf said: It is the speech of Allah, Exalted be He, to the people of Thamud by way of shifting the address toward them—either within the address of Allah, Exalted be He, to our Messenger, peace be upon him. This is analogous to what He, Glory be to Him, narrated about Shu‘ayb: "So he turned away from them and said, ‘O my people, I have certainly conveyed to you...’" after they had been utterly destroyed. This is among the most eloquent of speech, indicating that they are deserving of this threat, as if they were present in the assembly, and the face was turned toward them to denounce their crimes. Alternatively, it is within the address of the Almighty to Salih, peace be upon him, with the revealed text being a narrative of that speech which contains the shift in address. On both interpretations, there is no complication as some have imagined. The wording of al-Zamakhshari points more strongly to the former, and it is more eloquent. End quote. As for one who turns his attention to what the majority have said regarding the iltifat, I do not think his soul would find tranquility in what has been mentioned, so ponder this.

Mujahid—according to what the author of al-Lawami‘ mentioned—along with Abu Qays al-Awdi, read al-ushur with three dammahs and a light 'ra'. It is said: ashir and ashur, like hadhir and hudhur. The dammah on the shin is a dialectal variation, and the dammah on the hamzah follows it. Al-Kisa'i narrated from Mujahid the dammah on the shin without the hamzah, making it like nudus.

Abu Haywah read it as al-ashar, as a superlative form, meaning "the one most excessive in wickedness." Qatadah and Abu Qilabah also read it this way. It is rarely used, even if it is according to the original form, like al-akhayar in the saying of Ru'bah: "Bilal is the best of people, and the son of the best." Abu Hatim said: The Arabs hardly ever use al-akhayar or al-ashar except in the necessity of poetry, and he cited the verse. Al-Jawhari said: Al-ashar is not said except in a poor dialect.