Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: We came with the Messenger of Allah (peace and blessings be upon him) in the state of ihram for Hajj, and he (peace and blessings be upon him) ordered them to make it Umrah. Then he said: "Had I known beforehand what I came to know afterwards, I would have done as they did; but Umrah has entered into Hajj until the Day of Resurrection." Then he (peace and blessings be upon him) interlaced his fingers with one another, and the people came out of ihram, except those who had the sacrificial animal (hady) with them. And Ali (may Allah be pleased with him) came from Yemen, and the Messenger of Allah (peace and blessings be upon him) asked: "With what intention did you enter ihram?" He replied: I made the same intention that you made. He (peace and blessings be upon him) asked: "Do you have a sacrificial animal with you?" He replied: No. He (peace and blessings be upon him) said: "Then remain as you are, and one third of my sacrificial animals is yours." And the Messenger of Allah (peace and blessings be upon him) had sent one hundred camels as sacrificial animals.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11071