It is narrated from Hazrat Abu Bakrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: Jibreel and Mikaeel came to me. Jibreel said to me, "Recite the Noble Qur'an on one mode (harf)." Mikaeel said, "Request for an increase in it." Then Jibreel said, "You may recite the Noble Qur'an on seven modes (ahruf), any one of which is sufficient and satisfactory, provided that you do not change a verse of mercy into one of punishment, or a verse of punishment into one of mercy, such as 'ta'al' and 'aqbil', 'halumma' and 'idhhab', 'isra' and 'i'jil'."