Sahih Muslim 1230b

Muhammad ibn al-Muthanna narrated to us: Yahya—al-Qattan—narrated to us, from Ubayd Allah. Nafi informed me that Abdullah ibn Abdullah and Salim ibn Abdullah spoke to Abdullah ibn Umar when al-Hajjaj arrived to fight Ibn al-Zubayr. They said: It will not harm you if you do not perform Hajj this year. We fear fighting may break out among the people and prevent you from reaching the House. He said: If I am prevented from reaching it, I will do as I did with the Messenger of Allah when the unbelieving Quraysh prevented him from reaching the House. I call you to witness that I have made Umra obligatory upon myself. He set out until he came to Dhu al-Hulayfa and proclaimed the talbiya for Umra. Then he said: If the way is clear, I will complete my Umra; but if I am prevented from reaching it, I will do as I did with the Messenger of Allah. Then he recited: “Indeed, in the Messenger of Allah you have an excellent example.” He continued until he was behind al-Bayda and said: The two rites have one ruling. If I am prevented from Umra, I am prevented from Hajj as well. I call you to witness that I have made Hajj obligatory upon myself together with Umra. He continued until he bought a sacrificial animal at Qudayd, then performed one circumambulation of the House and one walk between al-Safa and al-Marwa for both rites. He did not exit ihram until he completed them on the Day of Sacrifice.