It is narrated from Ibn Abbas (may Allah be pleased with them both) that he said: "There is no impediment (ihsar) except the enemy." One of Ibn Tawus and Amr bin Dinar narrated these additional words: "Now even that (enemy's) impediment has ended."
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 942
It is narrated from Ibn Umar (may Allah be pleased with them both) that he said: "Whoever is prevented (due to illness), he should not exit the state of Ihram until he has performed the Tawaf of the House of Allah and the Sa'i between Safa and Marwah."
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 943
Hadith Takhrijأخرجه البخاري، المحصر، باب الاحصار في الحج (1810)۔
It is narrated from Abdullah bin Umar (may Allah be pleased with them) that he said: "Whoever is prevented from the House of Allah due to illness should not exit the state of Ihram until he has performed the Tawaf of the House of Allah and the Sa'i between Safa and Marwah."
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 944
Hadith Takhrijأخرجه البخاري، المحصر، باب الاحصار في الحج (1810)۔
It is narrated from Sulayman bin Yasar that Ibn Umar, Marwan, and Ibn Zubair (may Allah be pleased with them) gave a fatwa to Ibn Khuzamah al-Makhzumi, while he was afflicted with a headache on the way to Makkah and was also in the state of ihram. They said that he should seek treatment as much as possible, and gave him the fatwa that when he becomes healthy, he should perform ‘umrah and come out of ihram. Now it is obligatory upon him that he perform Hajj the following year and also offer a sacrifice.
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 945
Hadith Takhrijأخرجه البيهقي: 5/ 220 - وفى المعرفة السنن والآثار له (3254) - ومالك في الموطأ، الحج، باب ماجاء فيمن احصر بغير عدو۔