Jabir bin Zayd was asked about the prayer and its times, and he said: Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: "The time of the Fajr prayer is from the rising of dawn until the rays of the sun appear; after that its time ends. And the Messenger of Allah (peace and blessings be upon him) travelled by night, then halted to rest, and he (peace and blessings be upon him) did not wake until the sun had risen, or part of it had appeared; then he (peace and blessings be upon him) did not pray until the sun had risen high, and then he prayed. And this is 'al-Salat al-Wusta' (the middle prayer)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12775