Musnad Ahmad 27:1970

Yahya ibn Adam narrated to us, Mufaddal narrated to us, from Mansur, from Mujahid, who said: I entered the mosque with Urwah ibn al-Zubayr, and there was Ibn Umar leaning against the chamber of Aisha, while people were praying the Duha (forenoon) prayer. Urwah said to him, "O Abu Abd al-Rahman, what is this prayer?" He replied, "An innovation." Urwah said to him, "O Abu Abd al-Rahman, how many times did the Prophet, peace and blessings of Allah be upon him, perform Umrah?" He replied, "Four times, one of which was in Rajab." He said: And we heard the brushing of Aisha’s teeth in the chamber. Urwah said to her, "O Mother of the Believers, Abu Abd al-Rahman claims that the Prophet, peace and blessings of Allah be upon him, performed Umrah four times, one of which was in Rajab?" She replied, "May Allah have mercy on Abu Abd al-Rahman. The Prophet, peace and blessings of Allah be upon him, never performed an Umrah without him being with him, and he never performed Umrah in Rajab at all."