Muwatta Imam Malik Book of Hajj, Hadith 100

Yahya related to me from Malik from Nafi that when Abdullah ibn Umar set out for Makka during the troubles (between al-Hajjaj ibn Yusuf and Zubair ibn al-Awwam) he said, "If I am blocked from going to the House we shall do what we did when we were with the Messenger of Allah ﷺ" and he went into ihram for umra, because that was what the Messenger of Allah ﷺ did in the year of al-Hudaybiya.
But afterwards, he reconsidered his position and said, "It is the same either way." After that he turned to his companions and said, "It is the same either way. I call you to witness that I have decided in favour of hajj and umra together."
He then got through to the House (without being stopped) and did one set of tawaf, which he considered to be enough for himself, and sacrificed an animal.
Malik said, "This is what we go by if someone is hindered by an enemy, as the Prophet ﷺ and his companions were. If some one is hindered by anything other than an enemy, he is only freed from ihram by tawaf of the House. "

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّهُ قَالَ حِينَ خَرَجَ إِلَى مَكَّةَ مُعْتِمَرًا فِي الْفِتْنَةِ إِنْ صُدِدْتُ عَنِ الْبَيْتِ صَنَعْنَا كَمَا صَنَعْنَا مَعَ رَسُولِ اللَّهِ ﷺ فَأَهَلَّ بِعُمْرَةٍ مِنْ أَجْلِ أَنَّ رَسُولَ اللَّهِ ﷺ أَهَلَّ بِعُمْرَةٍ عَامَ الْحُدَيْبِيَةِ ثُمَّ إِنَّ عَبْدَ اللَّهِ نَظَرَ فِي أَمْرِهِ فَقَالَ مَا أَمْرُهُمَا إِلاَّ وَاحِدٌ ثُمَّ الْتَفَتَ إِلَى أَصْحَابِهِ فَقَالَ مَا أَمْرُهُمَا إِلاَّ وَاحِدٌ أُشْهِدُكُمْ أَنِّي قَدْ أَوْجَبْتُ الْحَجَّ مَعَ الْعُمْرَةِ . ثُمَّ نَفَذَ حَتَّى جَاءَ الْبَيْتَ فَطَافَ طَوَافًا وَاحِدًا وَرَأَى ذَلِكَ مُجْزِيًا عَنْهُ وَأَهْدَى .