Silsilat al-Ahadith al-Sahihah

Sayyiduna Anas (may Allah be pleased with him) says that the Prophet Muhammad (peace and blessings be upon him) was asked about the time of the Fajr prayer. In response, he (one day) offered the morning prayer at the time of the break of dawn, and (on another day) after the morning had become bright. Then he asked: "Where is the one who inquired about the Fajr prayer?" (Then, clarifying, he said:) "The time for this prayer is between these two times."