When ʿAbdullah bin ʿUmar set out for Mecca with the intentions performing ʿUmra in the period of afflictions, he said, "If I should be prevented from reaching the Kaʿba, then I would do the same as we did while in the company of Messenger of Allah ﷺ ." So, he assumed the Ihram for ʿUmra since the Prophet ﷺ had assumed the Ihram for ʿUmra in the year of Al-Hudaibiya. Then ʿAbdullah bin ʿUmar thought about it and said, "The conditions for both Hajj and ʿUmra are similar." He then turned towards his companions and said, "The conditions of both Hajj and ʿUmra are similar and I make you witnesses that I have made the performance of Hajj obligatory for myself along with ʿUmra." He then performed one Tawaf (between As-Safa and Al-Marwa) for both of them (i.e. Hajj and (ʿUmra) and considered that to be sufficient for him and offered a Hadi.  

حِينَ خَرَجَ إِلَى مَكَّةَ مُعْتَمِرًا فِي الْفِتْنَةِ إِنْ صُدِدْتُ عَنِ الْبَيْتِ صَنَعْنَا كَمَا صَنَعْنَا مَعَ رَسُولِ اللَّهِ ﷺ فَأَهَلَّ بِعُمْرَةٍ مِنْ أَجْلِ أَنَّ النَّبِيَّ ﷺ كَانَ أَهَلَّ بِعُمْرَةٍ عَامَ الْحُدَيْبِيَةِ ثُمَّ إِنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ نَظَرَ فِي أَمْرِهِ فَقَالَ مَا أَمْرُهُمَا إِلاَّ وَاحِدٌ فَالْتَفَتَ إِلَى أَصْحَابِهِ فَقَالَ مَا أَمْرُهُمَا إِلاَّ وَاحِدٌ أُشْهِدُكُمْ أَنِّي قَدْ أَوْجَبْتُ الْحَجَّ مَعَ الْعُمْرَةِ ثُمَّ طَافَ لَهُمَا طَوَافًا وَاحِدًا وَرَأَى أَنَّ ذَلِكَ مُجْزِيًا عَنْهُ وَأَهْدَى  

Ibn ʿUmar intended to perform Hajj in the year when Al-Hajjaj attacked Ibn Az-Zubair. Somebody said to Ibn ʿUmar, "There is a danger of an impending war between them." Ibn ʿUmar said, "Verily, in Messenger of Allah ﷺ you have a good example. (And if it happened as you say) then I would do the same as Messenger of Allah ﷺ had done. I make you witness that I have decided to perform ʿUmra." Then he set out and when he reached Al-Baida', he said, "The ceremonies of both Hajj and ʿUmra are similar. I make you witness that I have made Hajj compulsory for me along with ʿUmra." He drove (to Mecca) a Hadi which he had bought from (a place called) Qudaid and did not do more than that. He did not slaughter the Hadi or finish his Ihram, or shave or cut short his hair till the day of slaughtering the sacrifices (10th Dhul-Hijja). Then he slaughtered his Hadi and shaved his head and considered the first Tawaf (of Safa and Marwa) as sufficient for Hajj and ʿUmra. Ibn ʿUmar said, "Messenger of Allah ﷺ did the same."  

{لَقَدْ كَانَ لَكُمْ فِي رَسُولِ اللَّهِ أُسْوَةٌ حَسَنَةٌ} إِذًا أَصْنَعَ كَمَا صَنَعَ رَسُولُ اللَّهِ ﷺ إِنِّي أُشْهِدُكُمْ أَنِّي قَدْ أَوْجَبْتُ عُمْرَةً ثُمَّ خَرَجَ حَتَّى إِذَا كَانَ بِظَاهِرِ الْبَيْدَاءِ قَالَ مَا شَأْنُ الْحَجِّ وَالْعُمْرَةِ إِلاَّ وَاحِدٌ أُشْهِدُكُمْ أَنِّي قَدْ أَوْجَبْتُ حَجًّا مَعَ عُمْرَتِي وَأَهْدَى هَدْيًا اشْتَرَاهُ بِقُدَيْدٍ وَلَمْ يَزِدْ عَلَى ذَلِكَ فَلَمْ يَنْحَرْ وَلَمْ يَحِلَّ مِنْ شَىْءٍ حَرُمَ مِنْهُ وَلَمْ يَحْلِقْ وَلَمْ يُقَصِّرْ حَتَّى كَانَ يَوْمُ النَّحْرِ فَنَحَرَ وَحَلَقَ وَرَأَى أَنْ قَدْ قَضَى طَوَافَ الْحَجِّ وَالْعُمْرَةِ بِطَوَافِهِ الأَوَّلِ وَقَالَ ابْنُ عُمَرَ ؓ كَذَلِكَ فَعَلَ رَسُولُ اللَّهِ ﷺ