to something He had not been in, and the mountain beheld what it had never seen before.⦗1⦘
We then said to the Jahmi: “Is Allah light?” He replied, “He is nothing but light.” We answered, “Yet Allah says, ‘The earth will shine with the light of its Lord’ (az-Zumar 39:69). Thus Allah—exalted is His praise—has informed us that He possesses light.
“So tell us, when you claim that Allah is in every place and that He is light, why does a pitch-dark house not become brightened by the light that is supposedly within it if, as you allege, Allah is in every place? And why is it that when a lamp is brought into the room it gives light?”⦗2⦘
At that point it became clear to the people that they had lied about Allah, the Exalted. May Allah have mercy on anyone who reasons rightly about Allah, turns away from statements that conflict with the Quran and the Sunnah, embraces the position of the scholars—the position of the Muhajirun (Emigrants) and the Ansar (Helpers)—and abandons the creed of Satan and the creed of Jahm and his faction.⦗3⦘
(1) Ibn Batta, al-Ibana, 3/139-140: The Jahmi alleges that Allah is not absent from any place, yet Allah Himself has disproved him. Have you not heard His words: “When his Lord manifested Himself to the mountain, He reduced it to dust” (al-Araf 143)? The Jahmi is therefore asked: Did you see the mountain when He manifested Himself to it? And how could He have manifested Himself to the mountain if He were already inside it?
(2) Ibn Batta, al-Ibana, 3/140: Allah, Exalted is He, says: “The earth will shine with the light of its Lord” (al-Zumar 69). The Jahmi is asked, “Is Allah light?” He replies, “He is entirely light.” He is then asked, “So is Allah in every place?” He answers, “Yes.” We say: “Why, then, does a dark house not become luminous from the light that, according to you, is inside it, whereas a small lamp with a wick can be brought in and it lights up? How is it that the dark place in which, by your claim, Allah dwells remains unlit?” Thus the falsehood of the Jahmi and the gravity of his fabrication against his Lord become clear.
(3) Shaykh al-Islam Ibn Taymiyya, Bayan Talbis al-Jahmiyya, 1/592.