Narrated Al-Bara’:
I heard the Prophet (p.b.u.h) delivering a Khutba saying, “The first thing to be done on this day (first day of ‘Id 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).”
Sahih Bukhari, Volume 2, Book15, Number 71