The Cow - 2:185
Ramadan is the month in which the Qur´an was sent down, a guidance for mankind, a clear teaching and a book of law. Whoever reaches that month, let him fast. And those of you who are sick or traveling, fast on the other days for the number of days that you cannot fast. Allah desires ease for you and not hardship. So that you may complete the number (of fasting days) and glorify and give thanks to Allah Who has guided you to the truth.
"Ramadan is the month in which the Qur'an was revealed": Related
The Majesty/97:1
We sent it down on the Night of Power.
The Night Journey/17:106
It is a Qur´an which We set aside for the people to recite over a long period of time. We sent it down collectively