Sahih Muslim Book 32, Hadith Number 6331.

Chapter : He who goes in the mosque or in the bazaar or a place of gathering like it with a weapon should see that the spearhead does not harm anyone.

‘Amr heard Jabir as saying: A person happened to come to the mosque with an arrow; thereupon Allah’s Messenger (may peace be upon him) said to him: Take hold of its pointed head.