Quran 54:8 from Surah Al-Qamar on Divine Marvels.
مُّهۡطِعِينَ إِلَى ٱلدَّاعِۖ يَقُولُ ٱلۡكَٰفِرُونَ هَٰذَا يَوۡمٌ عَسِرٞ
English translation: Racing ahead toward the caller Will say the disbelievers This (is) a Day difficult
Transliteration: muh'ti'ina ila al-da'i yaqulu al-kafiruna hadha yawmun asirun