The Yawn and the Whisper

When a believer yawns during ṣalāh, the mouth must be covered at once; left uncovered, this becomes, as the Messenger of Allah (peace be upon him) states, one of the most delighted moments for Shayṭān, who exults over a worshipper heedless enough to yawn while standing before the Creator of the universe. In a different hadith he is said to enter and turn somersaults within the open mouth, delighting in a moment's absent-mindedness at the very task that matters most. Shayṭān's tricks in this regard are extensive, and every believer suffers from them to some degree — except those who worship Allah with complete sincerity, whom He protects, and this is no easy attainment. Shayṭān treats each believer as a personal target, and there is no freedom from him except by seeking refuge in Allah; the moment refuge is sought — Aʿūdhu billāhi min al-shayṭāni al-rajīm — he flees the heart.