Sulayman bin Yasar (may Allah have mercy on him) says that Habbar bin al-Aswad (may Allah be pleased with him) came on the Day of Sacrifice while Sayyiduna Umar (may Allah be pleased with him) was slaughtering his sacrifice. He said: O Commander of the Believers! We made a mistake; we thought today was the Day of Arafah. Sayyiduna Umar (may Allah be pleased with him) said: Go to Makkah, you and those with you, and perform seven circuits of tawaf around the House, and perform sa'y between Safa and Marwah. Then slaughter a sacrifice if you have one with you, then shave your heads or shorten your hair, and return. When the Hajj of the following year comes, perform Hajj and offer a sacrifice; and whoever does not have a sacrificial animal should fast three days during the days of Hajj and seven days after returning.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9822