Quran 68:33 from Surah Al-Qalam on Divine Marvels.
كَذَٰلِكَ ٱلۡعَذَابُۖ وَلَعَذَابُ ٱلۡأٓخِرَةِ أَكۡبَرُۚ لَوۡ كَانُواْ يَعۡلَمُونَ
English translation: Such (is) the punishment And surely the punishment (of) the Hereafter (is) greater if they know
Transliteration: kadhalika al-'adhabu wala'adhabu al-akhirati akbaru law kanu ya'lamuna