Tafsir of Al-Mutaffifeen 83:13

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,

وإذا قيل لهم ماذآ أنزل ربكم قالوا أسطير اﻻولين

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,

وقالوا أسطير اﻻولين اكتتبها فهى تملى عليه بكرة وأصيﻼ

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

كﻼ بل ران على قلوبهم ما كانوا يكسبون