Musannaf Ibn Abi Shaybah

Hazrat Abu Bakr narrates that Hazrat Jibreel said to the Noble Prophet (peace and blessings be upon him): Recite the Qur'an on one mode. Then Hazrat Mikaeel said to him: Increase in it. So Hazrat Jibreel said: Recite it on two modes! Then Mikaeel said: Increase in it, until it reached seven modes. Each of them is sufficient and complete, just as your saying "Halumma" and "Ta'al"—both have the same meaning: "Come." As long as he does not complete a verse of mercy with a verse of punishment, nor a verse of punishment with a verse of mercy.