Sahih Muslim , Book 35, Hadith 4 (In-Book) ⓘ

Jundab al-Bajali reported: I saw Allah's Messenger observing ('Id) prayer on the Day of Sacrifice (10th of Dhu'l-Hijja) and then delivering a sermon and he said: He who sacrificed the (animal) before offering ('Id) prayer, he should offer again in its stead, and he who did not sacrifice the animal should slaughter it by reciting the name of Allah.

حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُعَاذٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا شُعْبَةُ، عَنِ الأَسْوَدِ، سَمِعَ جُنْدَبًا الْبَجَلِيَّ، قَالَ شَهِدْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم صَلَّى يَوْمَ أَضْحًى ثُمَّ خَطَبَ فَقَالَ ‏ "‏ مَنْ كَانَ ذَبَحَ قَبْلَ أَنْ يُصَلِّيَ فَلْيُعِدْ مَكَانَهَا وَمَنْ لَمْ يَكُنْ ذَبَحَ فَلْيَذْبَحْ بِاسْمِ اللَّهِ ‏" ‏ ‏.‏