Meaning of oath of ten nights, the even, and the odd in Surat al-Fajr

from the Prophet ﷺ who said: 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).

عَنِ النَّبِيِّ ﷺ قَالَ «إِنَّ الْعَشْرَ عَشْرُ الْأَضْحَى وَالْوَتْرَ يَوْمُ عَرَفَةَ وَالشَّفْعَ يَوْمُ النَّحْرِ»