What does “wa-in khiltu” add to the poetic comparison with night?

Musāwāt and Ījāz al-Qaṣr: Proportionate Wording and the Rhetoric of Qiṣāṣ

• Being overtaken even despite the imagined possibility of escape
• The rule for an implied vocative
• Only a report about travel at night
• A technical term of rhyme