Sahih Bukhari Volume 003, Book 027, Hadith Number 004.
Narated By Mujahid : Ursa bin AzZubair and I entered the Mosque (of the Prophet) and saw 'Abdullah bin Umar sitting near the dwelling place of 'Aisha and some people were offering the Duha prayer. We asked him about their prayer and he replied that it was a heresy. He (Ursa) then asked him how many times the Prophet had performed 'Umra. He replied, 'Four times; one of them was in the month of Rajab." We disliked to contradict him. Then we heard 'Aisha, the Mother of faithful believers cleaning her teeth with Siwak in the dwelling place. 'Ursa said, "O Mother! O Mother of the believers! Don't you hear what Abu 'Abdur Rahman is saying?" She said, "What does he say?" 'Ursa said, "He says that Allah's Apostle performed four 'Umra and one of them was in the month of Rajab." 'Aisha said, "May Allah be merciful to Abu 'Abdur Rahman! The Prophet did not perform any 'Umra except that he was with him, and he never performed any 'Umra in Rajab."