The Saheeh International Quran Translation
وَقَالَ ٱلَّذِينَ كَفَرُوا۟ لَوْلَا نُزِّلَ عَلَيْهِ ٱلْقُرْءَانُ جُمْلَةً وَٰحِدَةً كَذَٰلِكَ لِنُثَبِّتَ بِهِۦ فُؤَادَكَ وَرَتَّلْنَٰهُ تَرْتِيلًا
تجهيز للطباعة
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.