Ata' bin Yasar (may Allah have mercy on him) narrates from Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him): One man would sacrifice one sheep on our behalf; then later people made it a means of showing off.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19053