Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)

Bukhari :: Book 5 :: Volume 59 :: Hadith 556

Narrated Ibn Abi Aufa:

When Allah's Apostle performed the 'Umra (which he performed in the year following the treaty of Al-Hudaibiya) we were screening Allah's Apostle from the infidels and their boys lest they should harm him.