In as-Sahih, it is mentioned that word al-ghassak (dusk) means the early part of the evening (just before sunset) and the night or darkness becomes apparent when the twilight has disappeared or ended. Thus, the meaning “from the evil of the utterly dark night when it comes” is appropriate.
The relationship between evil and night is established because darkness helps or assists the evil doer in his evil deeds and covers him. Therefore, there is more evil (carried out) at night rather than during day time and one also becomes more vulnerable to evil at night than during day time. It was said that what is meant by darkness (in the verse) is every evil doer who strikes by performing evil.
In this context, mentioning the evil of the night after the evil of what He has created, in the manner of mentioning the specific after the general, is for the purpose of emphasis. Allah (s.w.t) has drawn our close attention to three types of evil in this chapter – the evil of the night, the evil of the witchcrafts and the evil of the envious – because people are often heedless or inattentive to these things.
This refers to the sorceresses and witches who bewitch (others) by blowing into the knots. The Arabic wording is such that the “blowers” is in the feminine plural and the “knots” also in plural. The women have been specifically mentioned here because they seem to favour witchcraft (and magic) more than men. This affirms the impact of witchcraft in general just like Allah has said in the story of Harut and Marut:
Even then men learned from these two (Harut and Marut), magic by which they might cause a separation between a man and his wife; and they cannot hurt with it anyone except with Allah’s permission… (2:102)