Fa-la uqsimu bi-al-shafaq (So I swear by the twilight)

The twilight (al-shafaq) is the redness witnessed on the western horizon after sunset. Its root is derived from the thinness/delicacy of a thing; it is said of a thing that is shafaq when it does not hold together due to its thinness. From this is [the expression] ashfaqa 'alayhi (he felt compassion for him), meaning his heart became tender. Shafaqah (compassion) is derived from ishfaq (to show concern), as is al-shafaq (twilight). The poet said:

She desires my life, and I desire her death, Out of compassion; and death is the most noble guest to the sanctuary.

It is said that it is the whiteness that follows that redness, and it is reported [to occur] after its disappearance. There is a disagreement with the majority regarding the naming of that [whiteness] as shafaq, as they hold that it is not called by that name. Abu Hurairah, Umar ibn Abd al-Aziz, and Abu Hanifah—may Allah be pleased with them—are of the view that it is called by that name. It is reported from Asad ibn Amr, regarding Abu Hanifah—may Allah be pleased with him—that he retracted this view to that of the majority. The complete discussion on this is in the commentaries of al-Hidayah.

Abd ibn Humayd extracted from Mujahid and Ikrimah that it [the word shafaq] here refers to the entire day. This was also reported from al-Dahhak and Ibn Abi Najih, as if the [mention of the] night [that follows it] encouraged them to [interpret] it as such. It is also narrated from Ikrimah that it is what remains of the day.

The fa (So) in "So I swear" is the response to a conditional [clause] that is implied; that is, "If you have known this, or if you have realized the inevitability of resurrection, then I swear by the twilight."