Sahih Muslim Book - 35, Hadith - 5064

حَدَّثَنَا أَحْمَدُ بْنُ يُونُسَ ، حَدَّثَنَا زُهَيْرٌ ، حَدَّثَنَا الأَسْوَدُ بْنُ قَيْسٍ (ح) وَحَدَّثَنَاهُ يَحْيَى بْنُ يَحْيَى ، أَخْبَرَنَا أَبُو خَيْثَمَةَ ، عَنِ الأَسْوَدِ بْنِ قَيْسٍ ، حَدَّثَنِي جُنْدَبُ بْنُ سُفْيَانَ ، قَالَ: شَهِدْتُ الأَضْحَى مَعَ رَسُولِ اللهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ ، فَلَمْ يَعْدُ أَنْ صَلَّى وَفَرَغَ مِنْ صَلاَتِهِ سَلَّمَ ، فَإِذَا هُوَ يَرَى لَحْمَ أَضَاحِيَّ قَدْ ذُبِحَتْ قَبْلَ أَنْ يَفْرُغَ مِنْ صَلاَتِهِ ، فَقَالَ: مَنْ كَانَ ذَبَحَ أُضْحِيَّتَهُ قَبْلَ أَنْ يُصَلِّيَ ، أَوْ نُصَلِّيَ ، فَلْيَذْبَحْ مَكَانَهَا أُخْرَى ، وَمَنْ كَانَ لَمْ يَذْبَحْ ، فَلْيَذْبَحْ بِاسْمِ اللَّهِ.

Jundab bin Sufyan said: "I was present at ('Eid) Al-Adha with the Messenger of Allah (s.a.w), and no sooner had he finished his prayer, and said the Salam, but he saw the meat of some sacrifices that had been slaughtered before he had finished his prayer. He said: 'Whoever offered his sacrifice before the prayer - or before we prayed - let him offer another one in its stead, and whoever did not yet offer his sacrifice, let him offer it in the Name of Allah."'