Abu Dawud Book 1, Hadith Number 50.
Chapter : Using others toothstick.
Narated By ‘Aisha, Ummul Mu’minin : The Apostle of Allah (PBUH) was using the tooth-stick, when two men, one older than the other, were with him. A revelation came to him about the merit of using the tooth-stick. He was asked to show proper respect and give it to the elder of the two.