Sahih Bukhari
Fighting for the Cause of Allah (Jihaad)
Volume: 004 / Book Number: 052 / Hadith Number: 228
Narrated 'Abdur-Rahman bin Abi Bakr As-Siddiq:
The Prophet ordered me to let 'Aisha sit behind me (on the animal) and to let her perform 'Umra from At-Tan'im.