Sahih Bukhari: Hadith 942

I was with Ibn `Umar when a spear head pierced the sole of his foot and his foot stuck to the paddle of the saddle and I got down and pulled his foot out, and that happened in Mina. Al-Hajjaj got the news and came to inquire about his health and said, "Alas! If we could only know the man who wounded you!" Ibn `Umar said, "You are the one who wounded me." Al-Hajjaj said, "How is that?" Ibn `Umar said, "You have allowed the arms to be carried on a day on which nobody used to carry them and you allowed arms to be carried in the Haram even though it was not allowed before."