Sahih Bukhari Volume 3, Book 26, Hadith 1777

قَالَ وَسَمِعْنَا اسْتِنَانَ، عَائِشَةَ أُمِّ الْمُؤْمِنِينَ فِي الْحُجْرَةِ، فَقَالَ عُرْوَةُ يَا أُمَّاهُ، يَا أُمَّ الْمُؤْمِنِينَ‏.‏ أَلاَ تَسْمَعِينَ مَا يَقُولُ أَبُو عَبْدِ الرَّحْمَنِ‏.‏ قَالَتْ مَا يَقُولُ قَالَ يَقُولُ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم اعْتَمَرَ أَرْبَعَ عُمَرَاتٍ إِحْدَاهُنَّ فِي رَجَبٍ‏.‏ قَالَتْ يَرْحَمُ اللَّهُ أَبَا عَبْدِ الرَّحْمَنِ، مَا اعْتَمَرَ عُمْرَةً إِلاَّ وَهُوَ شَاهِدُهُ، وَمَا اعْتَمَرَ فِي رَجَبٍ قَطُّ‏

Then we heard 'Aisha, the Mother of faithful believers cleaning her teeth with Siwak in the dwelling place. 'Urwa 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."