Tafsir of Al-Kahf 18:49

{The Book} refers to the genus, meaning the records of deeds.

{Woe to us!} They call out their specific destruction from among all destructions.

{It leaves nothing small or great} meaning no small or great matter. This is an expression of encompassing; it means it does not leave any sin without recording it. It means it recorded them all, just as you would say, "He did not give me a little or a lot," because things are either small or large. It is also possible that it means they had both minor and major sins. It is said: They did not avoid the major sins, so the minor ones were recorded against them, which is the [process of] strict reckoning.

From Ibn Abbas: The small is smiling, and the large is loud laughter. From Sa'id ibn Jubayr: The small is touching, and the large is adultery. From al-Fudayl: When he read this, he would say, "By Allah, they lamented over the small sins before the large ones."

{Except that it has enumerated it} meaning it has registered and contained it.

{And they found what they did present} in the records, prepared. Or, they found the recompense for what they did.

{And your Lord does not wrong anyone} by writing against him what he did not do, or by increasing the punishment of one who deserves it, or by punishing him without a crime—as is claimed by those who accuse Allah of injustice in punishing the children of the polytheists for the sins of their fathers.

{And when We said to the angels, "Prostrate to Adam," and they prostrated, except Iblis. He was of the jinn and disobeyed the command of his Lord. Then will you take him and his descendants as allies other than Me while they are enemies to you? Wretched it is for the wrongdoers as an exchange. I did not make them witness the creation of the heavens and the earth or the creation of themselves, and I would not have taken the misguiders as assistants.}