Hadith 3416
Narrated Ubaydah ibn as-Samit: I taught some persons of the people of Suffah writing and the Quran. A man of them presented to me a bow. I said: It cannot be reckoned property; may I shoot with it in Allah's path? I must come to the Messenger of of Allah ﷺ and ask him (about it). So I came to him and said: Messenger of Allah ﷺ, one of those whom I have been teaching writing and the Quran has presented me a bow, and as it cannot be reckoned property, may I shoot with it in Allah's path? He said: If you want to have a necklace of fire on you, accept it.
Hadith 3417
A similar tradition has also been transmitted by Ubadah bin al-Samit through a different chain of narrators, but the former tradition is more perfect. This version has: I said: What do you think about it, Messenger of Allah? He said: A live coal between your shoulders which you have put around your neck or hanged it.