Tafsir of Ash-Shu`ara' 26:189

{فَكَذَّبُوهُ}: They persisted in denying him, and they denied him with denial after denial.

{فَأَخَذَهُمْ عَذَابُ يَوْمِ الظُّلَّةِ}: This occurred according to what was recorded by Abd ibn Humayd, Ibn Jarir, Ibn al-Mundhir, Ibn Abi Hatim, and al-Hakim from Ibn Abbas: Allah the Almighty sent upon them an intense heat that took hold of their breaths. They retreated into the interiors of their houses, but the heat entered upon them there as well. They fled from them to the open wilderness. Allah the Almighty then sent upon them a cloud that shaded them from the sun—this is "the shadow" (al-zulla). They found in it coolness and delight, so they called out to one another until they had all gathered beneath it. Allah, Glorified and Exalted, dropped it upon them as fire, consuming them all. It is stated in many narrations that Allah, Exalted and Majestic, unleashed the heat upon them for seven days and their nights, after which occurred what occurred regarding the escape to the wilderness and what followed. This was in accordance with the manner of what they had demanded, especially according to the view that by "the sky" they intended the clouds. Attributing the punishment to the "day" of the shadow rather than to the shadow itself signifies that they had another punishment besides the punishment of the shadow, and omitting its explanation serves to magnify its gravity.

Ibn Jarir, al-Hakim, and Ibn Abi Hatim recorded from Ibn Abbas (may Allah be pleased with them both) that he said: "Whoever among the scholars tells you what the punishment of the Day of the Shadow was, call him a liar." It is as if he meant by that the totality of the punishment of the shadow—which was mentioned in the previous report—and the other punishment which the attribution to the "day" signaled.

{إِنَّهُ كَانَ عَذَابَ يَوْمٍ عَظِيمٍ}: That is, in intensity, terror, and the horribleness of what occurred therein of catastrophe and complete calamity.