It is narrated from Abu Sa'id Al-Khudri, may Allah be pleased with him, that the Messenger of Allah, peace and blessings be upon him, said: "When one of you yawns, he should place his hand over his mouth, for the devil enters (into the mouth)." Narrated by Muslim.
Hadith Referenceمشكوة المصابيح / كتاب الآداب / 4737
Hadith Gradingالألبانی:صَحِيح | زبیر علی زئی:صحيح
Hadith Takhrij´تحقيق و تخريج: محدث العصر حافظ زبير على زئي رحمه الله` «رواه مسلم (2995/57)»