"Observer prayer from the declining and paling of the sun til the darkness of the night, and recite the Quran at dawn. Verily the recitation of the Quran at dawn is especially acceptable to Allah Quran (17:79)"
"Abu Hurairah relates that the Holy Prophet saw said: A succession of angels visits you during the night and also during the day and they get together during the dawn prayer and the afternoon prayer. Then those of them who had spent the night among you ascend to heaven and Allah inquires from them (though he knows better than they): What conditions do you leave my servants in? They answer: They were praying when we came to them and they were praying when we left them (Bokhari and Muslim)"