Concerning Allah's statement,

إِذَا تُتْلَى عَلَيْهِ آيَاتُنَا قَالَ أَسَاطِيرُ الْأَوَّلِينَ ﴿١٣﴾

When Our Ayat are recited to him, he says:

"Tales of the ancients!''

meaning, whenever he hears the Words of Allah from the Messenger , he denies it and has ill thoughts about it. Thus, he believes that it is a collection gathered from the books of the ancients.

This is as Allah says,

وَإِذَا قِيلَ لَهُمْ مَّاذَآ أَنزَلَ رَبُّكُمْ قَالُواْ أَسَـطِيرُ الاٌّوَّلِينَ

And when it is said to them: "What is it that your Lord has sent down''

They say: "Tales of the men of old!'' (16:24)

Similarly Allah says,

وَقَالُواْ أَسَـطِيرُ الاٌّوَّلِينَ اكْتَتَبَهَا فَهِىَ تُمْلَى عَلَيْهِ بُكْرَةً وَأَصِيلاً

And they say:

"Tales of the ancients, which he has written down: and they are dictated to him morning and afternoon.'' (25:5)