Messenger of Allah ﷺ addressed us on the day of 'Id al-Adha. He smelt the odour of flesh and he prohibited thern from slaughtering (the animals before the 'Id prayer), saying: He who slaughtered the animals (before the 'Id prayer) should do that again (as it is not valid as a sacrifice).
خَطَبَنَا رَسُولُ اللَّهِ ﷺ يَوْمَ أَضْحًى قَالَ فَوَجَدَ رِيحَ لَحْمٍ فَنَهَاهُمْ أَنْ يَذْبَحُوا قَالَ مَنْ كَانَ ضَحَّى فَلْيُعِدْ ثُمَّ ذَكَرَ بِمِثْلِ حَدِيثِهِمَا