Sahih Muslim Book 007, Hadith Number 2883.
Chapter : Concerning the Umras performed by Allah's Apostle (may peace be upon him) and their respective times.
Mujihid reported: I and 'Urwa h Zubair entered the mosque and there found 'Abdullah b. 'Umar sitting near the apartment of 'Aisha and the people were observing the forenoon prayer (when the sun bad sufficiently risen). We asked him about their prayer, and he said: It is bid'a (innovation), Urwa said to him: Abd al-Rahman, how many, 'Umras had Allah's Messenger (may peace be upon him) performed? He said: Four Umras, one he performed during the month of Rajab. We were reluctant either to belie him or reject him. We heard the noise of brushing of her teeth by 'Aisha in her apartment. 'Urwa said: Mother of the Faithful, are you not hearing what Abfi 'Abd al-Rahman is saying? She said: What is he saying? Thereupon he ('Urwa) said: He (Ibn 'Umar) states that Allah's Apostle (may peace be upon him) performed four Umras and one of them during the month of Rajab. Thereupon she remarked: May Allah have merely upon Abu 'Abd al-Rahman. Never did Allah's Messenger (may peace be upon him) perform 'Umra in which he did not accompany him, and he (Allah's Apostle) never performed 'Umra during the month of Rajab.