I heard the Prophet ﷺ delivering a Khutba saying, "The first thing to be done on this day (first day of ʿId ul Adha) is to pray; and after returning from the prayer we slaughter our sacrifices (in the name of Allah) and whoever does so, he acted according to our Sunna (traditions)."
سَمِعْتُ النَّبِيَّ ﷺ يَخْطُبُ فَقَالَ إِنَّ أَوَّلَ مَا نَبْدَأُ مِنْ يَوْمِنَا هَذَا أَنْ نُصَلِّيَ ثُمَّ نَرْجِعَ فَنَنْحَرَ فَمَنْ فَعَلَ فَقَدْ أَصَابَ سُنَّتَنَا