Sunan Abi Dawud Book 2, Hadith 440
The Messenger of Allah (ﷺ) came to us while we were reciting the Qur'an, and there were among us bedouins and the non-Arabs. He said: Recite, all is well. In the near future there will appear people who will straighten it (the Qur'an) as an arrow is straightened. They will recite it quickly and not slowly (or it means that they will get the reward in this world and not in the Hereafter).
Which of you did recite the surah “ Glorify the name of thy lord, the Most High”(Surah lxxxvii.) A man said: I . He said: I knew that some one of you confused me in it(i.e in the recitation of the Qur’an).
The Messenger of Allah(ﷺ) one day came out to us while we were reciting the Qur’an. He said: Praise be to Allah. The Book of Allah is one, and among you are the red, and among you are the white and among you are the black. Recite it before there appear people who will recite it and straighten it as an arrow is straightened. They will get their reward for it in this world and will not get it in the Hereafter.