Sahih Bukhari Volume 1, Book 9, Hadith 573

حَدَّثَنَا مُسَدَّدٌ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ إِسْمَاعِيلَ، حَدَّثَنَا قَيْسٌ، قَالَ لِي جَرِيرُ بْنُ عَبْدِ اللَّهِ كُنَّا عِنْدَ النَّبِيِّ صلى الله عليه وسلم إِذْ نَظَرَ إِلَى الْقَمَرِ لَيْلَةَ الْبَدْرِ فَقَالَ ‏"‏ أَمَا إِنَّكُمْ سَتَرَوْنَ رَبَّكُمْ كَمَا تَرَوْنَ هَذَا، لاَ تُضَامُّونَ ـ أَوْ لاَ تُضَاهُونَ ـ فِي رُؤْيَتِهِ، فَإِنِ اسْتَطَعْتُمْ أَنْ لاَ تُغْلَبُوا عَلَى صَلاَةٍ قَبْلَ طُلُوعِ الشَّمْسِ، وَقَبْلَ غُرُوبِهَا فَافْعَلُوا ‏"‏‏.‏ ثُمَّ قَالَ ‏"‏ فَسَبِّحْ بِحَمْدِ رَبِّكَ قَبْلَ طُلُوعِ الشَّمْسِ وَقَبْلَ غُرُوبِهَا ‏"

Narrated By Jarir bin 'Abdullah : We were with the Prophet on a full moon night. He looked at the moon and said, "You will certainly see your Lord as you see this moon, and there will be no trouble in seeing Him. So if you can avoid missing (through sleep, business, etc.) a prayer before the rising of the sun (Fajr) and before its setting ('Asr) you must do so. He (the Prophet) then recited the following verse: "And celebrate the praises Of Your Lord before The rising of the sun And before (its) setting."