The word(s) "لَيَالٍ" appears in 4 verse(s) in Quran.

(1) قَالَ رَبِّ اجْعَل لِّي آيَةً ۚ قَالَ آيَتُكَ أَلَّا تُكَلِّمَ النَّاسَ ثَلَاثَ لَيَالٍ سَوِيًّا

(سورة مريم, Maryam, Chapter #19, Verse #10)
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(2) وَجَعَلْنَا بَيْنَهُمْ وَبَيْنَ الْقُرَى الَّتِي بَارَكْنَا فِيهَا قُرًى ظَاهِرَةً وَقَدَّرْنَا فِيهَا السَّيْرَ ۖ سِيرُوا فِيهَا لَيَالِيَ وَأَيَّامًا آمِنِينَ

(سورة سبإ, Saba, Chapter #34, Verse #18)
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(3) سَخَّرَهَا عَلَيْهِمْ سَبْعَ لَيَالٍ وَثَمَانِيَةَ أَيَّامٍ حُسُومًا فَتَرَى الْقَوْمَ فِيهَا صَرْعَىٰ كَأَنَّهُمْ أَعْجَازُ نَخْلٍ خَاوِيَةٍ

(سورة الحاقة, Al-Haaqqa, Chapter #69, Verse #7)
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(4) وَلَيَالٍ عَشْرٍ

(سورة الفجر, Al-Fajr, Chapter #89, Verse #2)
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