صحيح البخاري

Narrated Anas bin Malik:

On the day of the Conquest, the Prophet (ﷺ) entered Mecca, wearing a helmet on his head. When he took it off, a man came and said, "Ibn Khatal is clinging to the curtain of the Ka`ba." The Prophet (ﷺ) said, "Kill him." (Malik a sub-narrator said, "On that day the Prophet (ﷺ) was not in a state of Ihram as it appeared to us, and Allah knows better.")