Abu Dawud Book 2, Hadith Number 1272.
Narated By Amr ibn Anbasah as-Sulami : I asked: Apostle of Allah, in which part of night the supplication is more likely to be accepted?
He replied: In the last part: Pray as much as you like, for the prayer is attended by the angels and it is recorded till you offer the dawn prayer; then stop praying when the sun is rising till it has reached the height of one or two lances, for it rises between the two horns of the Devil, and the infidels offer prayer for it (at that time). Then pray as much as you like, because the prayer is witnessed and recorded till the shadow of a lance be- comes equal to it. Then cease prayer, for at that time the Hell-fire is heated up and doors of Hell are opened.
When the sun declines, pray as much as you like, for the prayer is witnessed till you pray the afternoon prayer; then cease prayer till the sun sets, for it sets between the horns of the Devil, and (at that time) the infidels offer prayer for it. He narrated a lengthy tradition.
Abbas said: Abu Salam narrated this tradition in a similar manner from Abu Umamah. If I have made a mistake unintentionally, I beg pardon of Allah and repent to Him.