"In days of misfortune," meaning: ominous/unfortunate, and they are the eight days mentioned in [Surat] al-Haqqah, the first of which was Wednesday until the following Wednesday.

Muhammad said: The reading of Nafi' is (Nahsat) with the sukun on the Ha'. The singular of it is Nahs. The meaning is: they are [days of] misfortune upon them.

Interpretation of Surat Fussilat from verse 17 to verse 20.