Sahih Muslim Book 22, Hadith Number 4837.

Chapter : Of what age the animal is to be sacrificed.

Jabir b. ‘Abdullah reported: Allah’s Messenger (may peace be upon him) 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 (may peace be upon him) had-already offered sacrifice. Thereupon Allah’s Apostle (may peace be upon him) 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 (may peace be upon him) had sacrificed (his animal)