From Sahih Bukhari (Hadith 967):
Narrated Sa`id bin `Amr bin Sa`id 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)
Reference: Bukhari 967