General Behavior (Kitab Al-Adab)
Dawud :: Book 41 : Hadith 5011
Narrated AbuHurayrah:
When the Apostle of Allah (peace_be_upon_him) sneezed, he placed his hand or a garment on his mouth, and lessened the noise. The transmitter Yahya is doubtful about the exact words khafada or ghadda (lessened).