Tafsir of Al-Waqi'ah 56:41-56

20

That is, "Their prosperity had an adverse effect on them. Instead of being grateful to Allah Almighty, they had become deniers of His blessings. Lost in pleasure-seeking they had forgotten God and persisted in heinous sinning. "Heinous sinning" includes disbelief, polytheism and atheism as well as every grave sin of morality and conduct."

21

For the explanation of zaqqum, sec E.N. 34 of As-Saaffat.