Saying "Al-Hamdulillah" When Sneezing, Its Reply, and Manners Relating to Sneezing and Yawning
Abu Sa'id Al-Khudri (May Allah be pleased with him) reported: The Messenger of Allah (ﷺ) said, "When one yawns, he should put his hand over his mouth, otherwise the devil will enter."
[Muslim].
وعن أبي سعيد الخدري رضي الله عنه قال قال رسول الله صلى الله عليه وسلم إذا تثاءب أحدكم فليمسك بيده علي فيه فإن الشيطان يدخل ((رواه مسلم))