Musnad Abu Ya'la al-Mawsili 159:104

Narrated to us Dawud ibn Rashid, narrated to us Baqiyyah, from Mu'awiyah ibn Yahya, from Abu al-Zinad, from al-A'raj, from Abu Hurayrah, who said: The Messenger of Allah (peace be upon him) said: "Whoever is told a hadith, and then [the listener] sneezes in his presence, then it is true."