Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him), he says that the Messenger of Allah (peace and blessings be upon him) said: "The time for the beginning of a prayer is also the time for its end. The time for Zuhr begins when the sun declines (from its zenith), and when the time for Asr enters, the time for Zuhr ends. The first time for the Asr prayer is as it is, and when the sun becomes yellow, its (preferred) last time ends. The time for Maghrib begins at sunset and ends when the (red) twilight disappears from the horizon. The time for Isha begins when the (red) twilight disappears from the horizon and ends at midnight. The first time for Fajr begins at the appearance of dawn, and when the sun rises, its time ends."