Sahih Bukhari Volume 5, Book 64, Hadith 4185

حَدَّثَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ ـ رضى الله عنهما ـ خَرَجَ مُعْتَمِرًا فِي الْفِتْنَةِ فَقَالَ إِنْ صُدِدْتُ عَنِ الْبَيْتِ، صَنَعْنَا كَمَا صَنَعْنَا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم‏.‏ فَأَهَلَّ بِعُمْرَةٍ مِنْ أَجْلِ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ أَهَلَّ بِعُمْرَةٍ عَامَ الْحُدَيْبِيَةِ‏

Narrated By Nafi : Abdullah bin Umar set out for Umra during the period of afflictions, and he said, "If I should be stopped from visiting the Kaba, I will do what we did when we were with Allah's Apostle." He assumed Ihram for 'Umra in the year of Al-Hudaibiya.