Muslim recorded in his Sahih, and An-Nasa'i in his Book of Tafsir, in explaining this Ayah, from `Amr bin Hurayth that he said, "I prayed the Morning prayer behind the Prophet , and I heard him reciting,

﴿فَلاَ أُقْسِمُ بِالْخُنَّسِ - الْجَوَارِ الْكُنَّسِ - وَالَّيْلِ إِذَا عَسْعَسَ - وَالصُّبْحِ إِذَا تَنَفَّسَ ﴾

(But nay! I swear by Al-Khunnas, Al-Jawar Al-Kunnas, and by the night when it `As`as, and by the day when it Tanaffas.)'' Ibn Jarir recorded from Khalid bin `Ar`arah that he heard `Ali being asked about the Ayah; (لَا أُقْسِمُ بِالْخُنَّسِ. الْجَوَارِ الْكُنَّسِ) (Nay! I swear by Al-Khunnas, Al-Jawar Al-Kunnas.) and he said, "These are the stars that withdraw (disappear) during the day and sweep across the sky (appear) at night.'' Concerning Allah's statement,

﴿وَالَّيْلِ إِذَا عَسْعَسَ ﴾

(And by the night when it `As`as.) There are two opinions about this statement. One of them is that this refers to its advancing with its darkness. Mujahid said, "It means its darkening.'' Sa`id bin Jubayr said, "When it begins.'' Al-Hasan Al-Basri said, "When it covers the people.'' This was also said by `Atiyah Al-`Awfi. `Ali bin Abi Talhah and Al-`Awfi both reported from Ibn `Abbas:

﴿إِذَا عَسْعَسَ﴾

(when it `As`as) "This means when it goes away.'' Mujahid, Qatadah and Ad-Dahhak, all said the same. Zayd bin Aslam and his son `Abdur-Rahman also made a similar statement, when they said,

﴿إِذَا عَسْعَسَ﴾

(when it `As`as) "This means when it leaves, and thus it turns away.'' I believe that the intent in Allah's saying,

﴿إِذَا عَسْعَسَ﴾

(when it `As`as) is when it approaches, even though it is correct to use this word for departing also. However, approachment is a more suitable usage here. It is as if Allah is swearing by the night and its darkness when it approaches, and by the morning and its light when it shines from the east. This is as Allah says,

﴿وَالَّيْلِ إِذَا يَغْشَى - وَالنَّهَارِ إِذَا تَجَلَّى ﴾

(By the night as it envelops. By the day as it appears in brightness) (92:1-2) and He also says,

﴿وَالضُّحَى - وَالَّيْلِ إِذَا سَجَى ﴾

(By the forenoon. By the night when it darkens.) (93:1-2) Allah also says,

﴿فَالِقُ الإِصْبَاحِ وَجَعَلَ الَّيْلَ سَكَناً﴾

(Cleaver of the daybreak. He has appointed night for resting.) (6:96) And there are other similar Ayat that mention this. Many of the scholars of the fundamentals of language have said that the word `As`as is used to mean advancing and retreating, with both meanings sharing the same word. Therefore, it is correct that the intent could be both of them, and Allah knows best. Concerning Allah's statement,

﴿وَالصُّبْحِ إِذَا تَنَفَّسَ ﴾

(And by the day when it Tanaffas.) Ad-Dahhak said, "When it rises.'' Qatadah said, "When it brightens and advances.''