Surah Al-Fajr, verse 1

وَلَيَالٍ عَشْرٍۢ ﴿٢﴾

And [by] ten nights

وَٱلشَّفْعِ وَٱلْوَتْرِ ﴿٣﴾

And [by] the even [number] and the odd