وَالَّيْلِ

وَالَّيْلِ is a phrase (شِبْهُ الجُمْلَةِ) consisting of a particle of pulling down (a preposition) and a genitive noun

PhraseParticle / NounNoun Particle
شِبْهُ الجُمْلَةِجَارٌ وَمَجْرُوْرٌاسْمٌ مَجْرُوْرٌحَرْفُ جَرٍّ
PhraseCompoundGenitive NounParticle of pulling down/Preposition
  
by the nightوَالَّيْلِ=الَّيْلِ+وَ
 by the nightthe nightby
Surah/Below are the 7 verses in the holy Quran containing the compoundوَالَّيْلِ
Verse
74-33and the night when it departsوَالَّيْلِ إِذْ أَدْبَرَ
81-17and the night when it departsوَالَّيْلِ إِذَا عَسْعَسَ
84-17and the night and what it envelopsوَالَّيْلِ وَمَا وَسَقَ
89-4and the night when it departsوَالَّيْلِ إِذَا يَسْرِ
91-4and the night as it covers itوَالَّيْلِ إِذَا يَغْشَاهَا
92-1by the night as it envelopesوَالَّيْلِ إِذَا يَغْشَى
93-2and the night when it darkensوَالَّيْلِ إِذَا سَجَى