"إذا تثاءب أحدكم فليمسك بيده علي فيه، فإن الشيطان يدخل"
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] .