What is meant by the "witnessed Qur'an of Fajr"?

The meaning of "Qur'an of Fajr" in the verse: ﴿and the Qur'an of Fajr﴾ refers to the Fajr prayer. This is indicated by the Prophet's (peace be upon him) saying: "The congregational prayer is twenty-five degrees more virtuous than the prayer of an individual, and the angels of the night and the angels of the day gather at the Fajr prayer." Then Abu Hurayrah said: "Recite, if you wish: ﴿And the Qur'an of Fajr. Indeed, the Qur'an of Fajr is ever witnessed.﴾"