So that they will deny what We have granted them, and they will enjoy themselves. But they are going to know.1
Translation: Saheeh International (English)
1 Grammatically, the verse may also be read as a threat, i.e., "So let them deny what We have granted them and let them enjoy themselves, for they are going to know."
وَلِيَتَمَتَّعُواْۚand they may enjoy (themselves)waliyatamattaʿū
فَسَوۡفَBut soonfasawfa
يَعۡلَمُونَthey will knowyaʿlamūna
Tafsir
They return to their idolatry so that they can continue showing ingratitude for My favours upon them and so that they can carry on enjoying the beauty of the worldly life. They will soon know the evil punishment that awaits them when they die.