Sayyiduna Bara bin Azib (may Allah be pleased with him) narrates: My maternal uncle slaughtered the animal before the Prophet (peace and blessings of Allah be upon him) had performed the prayer. The Prophet (peace and blessings of Allah be upon him) said: Your goat is just a meat goat, it has nothing to do with sacrifice. He said: O Messenger of Allah (peace and blessings of Allah be upon him)! I have a six-month-old kid goat which is better than a one-year-old animal. The Prophet (peace and blessings of Allah be upon him) said: It will be sufficient for you, but it will not be sufficient for anyone after you.
Hadith Referenceصحیح ابن حبان / كتاب الأضحية / 5911
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح: ق - انظر ما قبله.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط الشيخين