Sahih al-Bukhari 7400
Sahih al-Bukhari · Book 97: Oneness, Uniqueness of Allah (Tawheed) · Asking Allah with His Names and seeking refuge with them
Narrated Jundab:
حَدَّثَنَا حَفْصُ بْنُ عُمَرَ ، حَدَّثَنَا شُعْبَةُ ، عَنِ الأَسْوَدِ بْنِ قَيْسٍ ، عَنْ جُنْدَبٍ ، أَنَّهُ شَهِدَ النَّبِيَّ صلى الله عليه وسلم يَوْمَ النَّحْرِ صَلَّى ثُمَّ خَطَبَ فَقَالَ " مَنْ ذَبَحَ قَبْلَ أَنْ يُصَلِّيَ فَلْيَذْبَحْ مَكَانَهَا أُخْرَى، وَمَنْ لَمْ يَذْبَحْ فَلْيَذْبَحْ بِاسْمِ اللَّهِ " .
That he witnessed the Prophet (ﷺ) on the Day of Nahr. The Prophet (ﷺ) offered prayer and then delivered a sermon saying, "Whoever slaughtered his sacrifice before offering prayer, should slaughter another animal in place of the first; and whoever has not yet slaughtered any, should slaughter a sacrifice and mention Allah's Name while doing so."