Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrated a long hadith, in which it was also mentioned that when the Messenger of Allah (peace and blessings be upon him) reached Makkah, he said to the people: "Whoever has brought a sacrificial animal should not come out of the restriction of anything that has been made forbidden until he completes his Hajj; and whoever has no sacrificial animal should perform tawaf of the House of Allah and of Safa and Marwah, have his hair shortened and leave ihram; then he should say the talbiyah for Hajj and offer a sacrifice; and whoever does not find a sacrificial animal should fast three days during the days of Hajj and seven on returning home."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 8888