Ash-Shams • EN-AL-JALALAYN
﴿ وَٱلَّيْلِ إِذَا يَغْشَىٰهَا ﴾
“and the night as it veils it darkly!”
and by the night when it enshrouds her covering her up with its darkness idhā ‘when’ in all three instances is an absolute adverbial operated by the verbal action of the oath.