Mutarrif bin Abdullah (may Allah have mercy on him) said: Sayyiduna Imran bin Husayn (may Allah be pleased with him) said to me: Shall I not narrate to you a hadith by which Allah may perhaps benefit you? The Messenger of Allah (peace and blessings be upon him) combined Hajj and Umrah; then no Qur'an was revealed that made it unlawful, and he (peace and blessings be upon him) did not forbid it until he (peace and blessings be upon him) passed away. A man said, from his own opinion, whatever he wished.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15339
Sayyiduna Imran bin Husayn (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) combined Hajj and Umrah. Then he narrated a similar hadith.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15340
It is narrated from Sayyiduna Imran (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) had a group of his family perform Umrah during the ten days of Dhu al-Hijjah.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15341
Sayyiduna Imran bin Husayn (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) entered ihram for both Hajj and Umrah.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15342