Sunan ad-Darimi

Abdullah and Salim, the sons of Abdullah bin Umar (may Allah be pleased with them), spoke to their father during the days before the battle when Hajjaj had set out against Ibn Zubair (may Allah be pleased with him). Both of them (the sons) said: There is no harm if you do not perform Hajj this year; we fear that you may be prevented from reaching the House of Allah. Abdullah bin Umar (may Allah be pleased with them) said: We set out with the Messenger of Allah (peace and blessings be upon him) with the intention of performing Umrah, but the disbelievers of Quraysh prevented us from reaching the House of Allah. So the Messenger of Allah (peace and blessings be upon him) slaughtered his camel there, shaved his head, and then returned from there. I make you witnesses that I have resolved to perform Umrah; if I am not prevented from reaching the Ka'bah, I will perform the Tawaf of the Ka'bah, and if I am prevented, I will do as the Messenger of Allah (peace and blessings be upon him) did, and I was with him. So he (Abdullah bin Umar, may Allah be pleased with them) entered into the state of Ihram for Umrah from Dhul-Hulaifah and set out, then said: The matter of Hajj and Umrah is one and the same. I make you witnesses that I have made Hajj obligatory along with Umrah (i.e., he intended Hajj Qiran). Nafi' said: Then he performed one Tawaf and one Sa'i for both Hajj and Umrah, and did not come out of Ihram until the day of sacrifice. And he (Abdullah bin Umar, may Allah be pleased with them) used to say: Whoever combines Umrah and Hajj and enters into Ihram for both, he should not come out of Ihram until he has completed both (i.e., he should not exit Ihram until he has finished both Hajj and Umrah).