Sunan an-Nasai Book 43, Hadith 4398

أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا أَبُو عَوَانَةَ، عَنِ الأَسْوَدِ بْنِ قَيْسٍ، عَنْ جُنْدُبِ بْنِ سُفْيَانَ، قَالَ ضَحَّيْنَا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم أَضْحَى ذَاتَ يَوْمٍ فَإِذَا النَّاسُ قَدْ ذَبَحُوا ضَحَايَاهُمْ قَبْلَ الصَّلاَةِ فَلَمَّا انْصَرَفَ رَآهُمُ النَّبِيُّ صلى الله عليه وسلم أَنَّهُمْ ذَبَحُوا قَبْلَ الصَّلاَةِ فَقَالَ ‏ "‏ مَنْ ذَبَحَ قَبْلَ الصَّلاَةِ فَلْيَذْبَحْ مَكَانَهَا أُخْرَى وَمَنْ كَانَ لَمْ يَذْبَحْ حَتَّى صَلَّيْنَا فَلْيَذْبَحْ عَلَى اسْمِ اللَّهِ عَزَّ وَجَلَّ ‏"‏ ‏.‏

It was narrated that Jundab bin Sufyan said:"We slaughtered the sacrifice with the Messenger of Allah on day, and the people slaughtered their sacrifices before the prayer. When he finished (the prayer) the Prophet saw that they had slaughtered their sacrifices before the prayer. He said: "Whoever slaughtered his sacrifice before the prayer, let him slaughter another in its place, and whoever did not slaughter his sacrifice until we had prayed, let him slaughter it in the name of Allah, The Mighty and Sublime," (Sahih)