وَقَالَ ٱلَّذِينَ كَفَرُواْ لَوۡلَا نُزِّلَ عَلَيۡهِ ٱلۡقُرۡءَانُ جُمۡلَةٗ وَٰحِدَةٗۚ كَذَٰلِكَ لِنُثَبِّتَ بِهِۦ فُؤَادَكَۖ وَرَتَّلۡنَٰهُ تَرۡتِيلٗا
Wa qaalal lazeena kafaroo law laa nuzzila 'alaihil Quraanu jumlatanw waahidah; kazaalika linusabbita bihee fu'aadaka wa rattalnaahu tarteelaa
English Translation
And those who disbelieve say, "Why was the Qur'an not revealed to him all at once?" Thus [it is] that We may strengthen thereby your heart. And We have spaced it distinctly
— Saheeh International