And they remained in their cave three hundred years. He means by their remaining in it alive, struck upon their ears for this duration. This is an explanation of what was summarized in His saying: 'So We struck upon their ears in the cave for a number of years.' The meaning of His saying: 'Say, Allah knows best what they remained' is that He knows better than those who differed about them regarding the duration of their stay. The truth is what Allah has informed you of. And from Qatadah: it is a narration of the words of the People of the Book. And 'Say, Allah knows best' is a response to them. And it was said in the reading of Abdullah: 'And they said they remained.' 'And years' is an apposition to three hundred. And it was read: three hundred years, in addition, placing the plural in the position of the singular in differentiation, like His saying: 'the greatest losers in deeds.' And in the reading of Ubayy: three hundred years, nine years, because what precedes indicates it. And Al-Hasan read: nine with a fathah. Then it mentioned His exclusivity regarding what is hidden in the heavens and the earth, and what is concealed in it from the conditions of its inhabitants and others, and that He alone is the All-Knowing of it. And it came with what indicates astonishment at His perception of sounds and sights, to show that His matter in perception is beyond the limits of what the hearers and seers are capable of, for He perceives the subtlest and smallest of things, just as He perceives the largest in size and densest in mass, and He perceives the hidden as He perceives the apparent. They have no protector among the inhabitants of the heavens and the earth who governs their affairs, nor does He share His judgment with anyone of them. And Al-Hasan read: 'And do not associate,' with a ت and in the jussive form as a prohibition.