Muhammad bin Ibrahim bin al-Harith محمد بن إبراهيم بن الحارث · The Book of Hajj

"O Messenger of Allah, my fater is an old man and he cannot perform Hajj or 'Umrah, nor can he travel." He said: "Perform Hajj and 'Umrah on behalf of your father."(sahih)

"They used to think that performing 'Umrah during the months of Hajj was one of the worst of evil actions on Earth, and they used to call Muharram 'Safar,' and say: 'When the sore on the backs of the camels have healed and when their hair grows back and when Safar is over' - or he said: 'When Safar beings - then 'Umrah becomes permissible for whoever wants to do it.' Then the Prophet and his companions came on the…

"We went out with the Messenger of Allah with no intention but Hajj. When he had circumambulated the Hosue and performed Sai between As-Safa and Al-Marwah, he said: 'Whoever has a Hadi with him, let him remain in Ihram, and whoever does not have a Hadi with him, let him exit Ihram.'"