Al-Kāfi - Volume 3 > The Times of Maghrib and ‘Isha’ Salah (Prayer)
Hadith #3

3ـ عَلِيُّ بْنُ مُحَمَّدٍ وَمُحَمَّدُ بْنُ الْحَسَنِ عَنْ سَهْلِ بْنِ زِيَادٍ عَنِ ابْنِ مَحْبُوبٍ عَنْ أَبِي وَلاَّدٍ قَالَ قَالَ أَبُو عَبْدِ الله (عَلَيْهِ الْسَّلام) إِنَّ الله خَلَقَ حِجَاباً مِنْ ظُلْمَةٍ مِمَّا يَلِي الْمَشْرِقَ وَوَكَّلَ بِهِ مَلَكاً فَإِذَا غَابَتِ الشَّمْسُ اغْتَرَفَ ذَلِكَ الْمَلَكُ غُرْفَةً بِيَدِهِ ثُمَّ اسْتَقْبَلَ بِهَا الْمَغْرِبَ يَتْبَعُ الشَّفَقَ وَيُخْرِجُ مِنْ بَيْنِ يَدَيْهِ قَلِيلاً قَلِيلاً وَيَمْضِي فَيُوَافِي الْمَغْرِبَ عِنْدَ سُقُوطِ الشَّفَقِ فَيُسَرِّحُ [فِي الظُّلْمَةِ] الظُّلْمَةَ ثُمَّ يَعُودُ إِلَى الْمَشْرِقِ فَإِذَا طَلَعَ الْفَجْرُ نَشَرَ جَنَاحَيْهِ فَاسْتَاقَ الظُّلْمَةَ مِنَ الْمَشْرِقِ إِلَى الْمَغْرِبِ حَتَّى يُوَافِيَ بِهَا الْمَغْرِبَ عِنْدَ طُلُوعِ الشَّمْسِ.

3. Ali ibn Muhammad and Muhammad ibn al-Hassan from Sahl ibn Ziyad from ibn Mahbub from abu Wallad Who has said the following: "Abu ’Abd Allah, ‘Alayhi al-Salam, has said, ‘Allah has created a barrier of darkness from near the east and has appointed for it an angel. When it is sunset, that angel fills up his hand with it, then faces toward the west, following the brightness and it moves out of his two hands little by little. He passes by until he comes to the west at the time of the disappearance of brightness; then he leaves darkness into darkness, then he returns to the east and, when it is dawn, he spreads his wings and drives the darkness from the east toward the west until he comes in the west at sunrise.’"