What is the evidence from the Qur’an, Sunnah, and scholarly opinions regarding the obligation of performing the Fajr prayer before sunrise?

Allah has made it obligatory to perform prayers at their appointed times and has warned those who neglect or delay them without a valid excuse of punishment, for "Indeed, prayer has been decreed upon the believers at specified times." Ibn Abbas interpreted neglecting prayer as delaying it, and Sa'd ibn Abi Waqqas interpreted being unmindful of it as wasting time in amusement until the prayer time expires, based on Allah's saying: "So woe to those who pray, [But] who are heedless of their prayer." The time for Fajr prayer extends until sunrise, and whoever catches one rak'ah before sunrise has caught it.