Musannaf Ibn Abi Shayba 3:845

Ibn Fudayl narrated to us, from al-A’mash, from Abu Salih, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, for the prayer there is a beginning and an end. The beginning of the time for Dhuhr is when the sun passes the meridian, and the end of its time is when the time for Asr enters. The beginning of the time for Asr is when the time for Asr enters, and the end of its time is when the sun turns yellow. The beginning of the time for Maghrib is when the sun sets, and the end of its time is when the horizon disappears. The beginning of the time for the final Isha is when the horizon disappears, and the end of its time is when the night reaches its middle. The beginning of the time for Fajr is when the dawn rises, and the end of its time is when the sun rises."