Sahih Bukhari Volume 2, Book 15, Hadith Number 84

Narated By Said bin ‘Amr bin Said bin Al-‘Aas : Al-Hajjaj went to Ibn Umar while I was present there. Al-Hajjaj asked Ibn Umar, “How are you?” Ibn Umar replied, “I am all right,” Al-Hajjaj asked, “Who wounded you?” Ibn Umar replied, “The person who allowed arms to be carried on the day on which it was forbidden to carry them (he meant Al-Hajjaj)”