وَقَالَ ٱلَّذِينَ كَفَرُوا۟ لَوْلَا نُزِّلَ عَلَيْهِ ٱلْقُرْءَانُ جُمْلَةً وَٰحِدَةً ۚ كَذَٰلِكَ لِنُثَبِّتَ بِهِۦ فُؤَادَكَ ۖ وَرَتَّلْنَـٰهُ تَرْتِيلًا
Wa qaalal lazeena kafaroo law laa nuzzila 'alaihil Quraanu jumlatanw waahidah; kazaalika linusabbita bihee fu'aadaka wa rattalnaahu tarteelaa
And those who deny say, "Why was the Qur'an not sent down to him all at once?" It is so — that we may steady your heart with it, and we have recited it in measured stages.