Sayyiduna Imran bin Husayn (may Allah be pleased with him) said: Know that the Messenger of Allah (peace and blessings be upon him) had a group of his family perform Umrah in the ten days of Dhu al-Hijjah. Then the Messenger of Allah (peace and blessings be upon him) did not forbid it, nor was any Qur'an revealed about it. Then a man said by his own opinion whatever he wished.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15304