وَعَنْهُ أَيْضًا عَنْ أَبِيهِ رَضِيَ اللَّهُ عَنْهُ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ إِذَا تَثَاءَبَ أَحَدُكُمْ فِي الصَّلَاةِ فَلْيَضَعْ يَدَهُ عَلَى فِيهِ فَإِنَّ الشَّيْطَانَ يَدْخُلُ مَعَ التَّثَاؤُبِ
Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) also narrates that the Noble Prophet (peace and blessings be upon him) said: When any of you yawns during prayer, he should place his hand over his mouth, because Satan enters the mouth along with the yawn.