It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Allah Almighty loves sneezing and dislikes yawning. When one of you sneezes and says 'Alhamdulillah' (All praise is for Allah), it is a duty upon the Muslim who hears him to say 'Yarhamuk Allah' (May Allah have mercy on you). And yawning is from Satan, so when one of you yawns, let him try to suppress it, for when one of you makes a sound (like 'haa') while yawning, Satan laughs."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3575
Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Yawning is from Satan, so when one of you yawns, let him try to suppress it as much as he is able."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3576
It is narrated from Sayyiduna 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 in prayer, let him suppress it as far as he can, for through yawning Satan enters."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3577
A hadith like it is reported through another chain, except that in it is: "Let him place his hand over his mouth," and in this narration he did not mention the prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3578