Amir narrates from Sayyiduna al-Bara bin Azib (may Allah be pleased with him) that one day the Messenger of Allah (peace and blessings be upon him) led us in prayer and said: "Whoever prays as we pray and faces our qiblah should not slaughter the sacrifice before the prayer (is finished)." Abu Burdah bin Niyar (may Allah be pleased with him) said: "O Messenger of Allah! I have slaughtered my animal." He (peace and blessings be upon him) said: "You have been hasty." Abu Burdah (may Allah be pleased with him) said: "I have a jadh'ah that is better than a two-toothed animal; shall I slaughter it?" He (peace and blessings be upon him) said: "Sacrifice it, but it will not suffice for any person after you."
Amir said: So it was the better of the two sacrifices.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19111