The Worst People are Those Who turn away after being reminded
Allah says,
ومن أظلم ممن ذكر بايات ربه فٲعرض عنها
And who does more wrong than he who is reminded of the Ayat (signs) of his Lord, but turns away from them,
Allah says, `Who among My creatures does more wrong than one who is reminded of the signs of Allah then turns away from them,' i.e., ignores them and does not listen or pay attention to them.
ونسي ما قدمت يداه
forgetting what his hands have sent forth.
means, bad deeds and evil actions.
إنا جعلنا على قلوبهم
Truly, We have set over their hearts,
means, the hearts of these people,
أكنة
Akinnah,
means, coverings.
أن يفقهوه
lest they should understand this,
means, so that they will not understand this Qur'an and its clear Message.
وفي آذانهم وقرا
and in their ears, deafness.
means that they will be deaf in an abstract way, to guidance.
وإن تدعهم إلى الهدى فلن يهتدوا إذا أبدا
And if you call them to guidance, even then they will never be guided