the Messenger of Allah ﷺ said, regarding "By the Dawn; and the Ten Nights" (Fajr 2): The ten are the ten of ˹days˺ of Adha (Dhu al-Hijjah), the odd is the Day of Arafah, and the even is the Day of Nahr (sacrifice).

قَالَ رَسُولُ اللَّهِ ﷺ {وَالْفَجْرِ وَلِيَالٍ عَشْرٍ} [الفجر 1] «عَشْرُ الْأُضْحِيَّةِ وَالْوِتْرُ يَوْمُ عَرَفَةَ وَالشَّفْعُ يَوْمُ النَّحْرِ»