(23) باب كَلاَمِ الإِمَامِ وَالنَّاسِ فِي خُطْبَةِ الْعِيدِ، وَإِذَا سُئِلَ الإِمَامُ عَنْ شَيْءٍ وَهْوَ يَخْطُبُ
Narrated Jundab:
On the day of Nahr the Prophet (ﷺ) offered the prayer and delivered the Khutba and then slaughtered the sacrifice and said, "Anybody who slaughtered (his sacrifice) before the prayer should slaughter another animal in lieu of it, and the one who has not yet slaughtered should slaughter the sacrifice mentioning Allah's name on it."
Reference: Sahih al-Bukhari 985
In-book reference: Book 13, Hadith 34
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 15, Hadith 101