Hadith: The Messenger of Allah (may Allah's peace and blessings be upon him) entered Makkah in the Year of the Conquest wearing a helmet on his head. When he took it off, a man came to him and said: Ibn Khatal is hanging on to the drapes of the Ka‘bah, so he (the Prophet, may Allah's peace and blessings be upon him) said: Kill him

عن أنس بن مالك رضي الله عنه : «أن رسول الله صلى الله عليه وسلم دخل مكة عام الفَتح، وعلى رأسه المِغْفَرُ، فلما نَزعه جاءه رجل فقال: ابن خَطَلٍ متعَلِّقٌ بأستار الكعبة، فقال: اقْتُلُوهُ».
[صحيح] - [متفق عليه]

Anas ibn Mālik (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) entered Makkah in the Year of the Conquest wearing a helmet on his head. When he took it off, a man came to him and said: "Ibn Khatal is hanging on to the drapes of the Ka‘bah." So he (the Prophet, may Allah's peace and blessings be upon him) said: "Kill him."
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

There was a covenant between the Prophet (may Allah's peace and blessings be upon him) and the disbelievers of the tribe of Quraysh, and he had declared that some of the polytheists were no longer granted immunity by the Muslims. They were nine people only. So, at the time of the conquest of Makkah, the Prophet (may Allah's peace and blessings be upon him) entered it while being on his guard, so he was wearing a helmet. Some of the Companions found Ibn Khatal (the apostate; one of those who were deprived of immunity) hanging on to the curtains of the Ka‘bah, seeking refuge in its sacredness against being killed, as he knew well how ugly and evil his past actions were. The Companions abstained from killing him before asking the Prophet (may Allah's peace and blessings be upon him). When they asked him, he said: "Kill him." So he was killed between the Black Stone and the Maqām Ibrahīm.