Whenever the Messenger of Allah (may Allah's peace and blessings be upon him) " sneezed, he would cover his mouth with his hand or cloth, suppressing or lowering (the narrator was unsure), the sound therewith" .[At-Tirmidhi]

عن أبي هريرة -- قال: كان رسول الله -صلى الله عليه وسلم- إذا عطس وضع يده أو ثوبه على فيه، وخفض -أو غض- بها صوته (الترمذي)