Al Furqan Ayah 32

وَقَالَ ٱلَّذِينَ كَفَرُواْ لَوْلَا نُزِّلَ عَلَيْهِ ٱلْقُرْءَانُ جُمْلَةً وَٲحِدَةً‌ۚ كَذَٲلِكَ لِنُثَبِّتَ بِهِۦ فُؤَادَكَ‌ۖ وَرَتَّلْنَـٰهُ تَرْتِيلاً ٣٢ The disbelievers say, “If only the Quran had been sent down to him all at once!” ?We have sent it? as such ?in stages? so We may reassure your heart with it. And We have revealed it at a deliberate pace.