And those who disbelieve say: "Why is not the Quran revealed to him all at once?" Thus (it is sent down in parts), that We may strengthen your heart thereby. And We have revealed it to you gradually, in stages. (It was revealed to the Prophet SAW in 23 years.).
و كسانى كه كافر شدند، گفتند: «چرا قرآن يكجا بر او نازل نشده است؟» اين گونه [ما آن را به تدريج نازل كرديم‌] تا قلبت را به وسيله آن استوار گردانيم، و آن را به آرامى [بر تو] خوانديم.