Mujahid said that by «غاسق‏» is meant the night. By «إذا وقب‏» is meant the setting of the sun. «فرق» and «فلق» have the same meaning; they say that this matter is clearer than «فرق» morning or «فلق» morning. The Arabs use «وقب‏» when something completely enters into something else and darkness occurs.

Narrated Zirr bin Hubaish: I asked Ubai bin Ka`b regarding the two Muwwidhat (Surats of taking refuge with Allah). He said, "I asked the Prophet about them, He said, 'These two Surats have been recited to me and I have recited them (and are present in the Qur'an).' So, we say as Allah's Messenger said (i.e., they are part of the Qur'an."