Jabir b. 'Abdullah reported:
Allah's Messenger (ﷺ) led us in the 'Id prayer in Medina on the Day of Sacrifice. Some persons slaughtered their animals ahead of him under the impression that Allah's Apostle (ﷺ) had-already offered sacrifice. Thereupon Allah's Apostle (ﷺ) said: Those who had slaughtered their animals ahead of him should slaughter the other ones in their stead. And they should not sacrifice the animal before Allah's Messenger (ﷺ) had sacrificed (his animal)
