Sunan an-Nasa'i 552
It was narrated that Anas bin Malik said:
"The Messenger of Allah (ﷺ) used to pray Zuhr when the sun passed its zenith, and he would pray 'Asr between these two prayers; and he would pray Maghrib when the sun had set, and he used to pray 'Isha' when the twilight had disappeared," then he said straight after that: "And he would pray Fajr when a man could see clearly."
أَخْبَرَنَا إِسْمَاعِيلُ بْنُ مَسْعُودٍ، وَمُحَمَّدُ بْنُ عَبْدِ الأَعْلَى، قَالاَ حَدَّثَنَا خَالِدٌ، عَنْ شُعْبَةَ، عَنْ أَبِي صَدَقَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُصَلِّي الظُّهْرَ إِذَا زَالَتِ الشَّمْسُ وَيُصَلِّي الْعَصْرَ بَيْنَ صَلاَتَيْكُمْ هَاتَيْنِ وَيُصَلِّي الْمَغْرِبَ إِذَا غَرَبَتِ الشَّمْسُ وَيُصَلِّي الْعِشَاءَ إِذَا غَابَ الشَّفَقُ - ثُمَّ قَالَ عَلَى إِثْرِهِ - وَيُصَلِّي الصُّبْحَ إِلَى أَنْ يَنْفَسِحَ الْبَصَرُ ‏.‏