The son of Abu Said al-Khudri reported on the authority of his father that Allah's Messenger (ﷺ) said. When one of you yawns while engaged in prayer, he should try to restrain so far as it lies in his power, since it is the Satan that enter therein.
Hadith ReferenceSahih Muslim / The Book of Zuhd and Softening of Hearts / Hadith: 2995