The Messenger of Allah ﷺ said, "Yawning comes from Satan, so when one of you yawns, let him suppress it as much as he can."
وبهذا الإسناد أن رسول الله ﷺ قال إن التثاؤب من الشيطان فإذا تثاءب أحدكم فليكظم ما استطاع
Its chain of transmission is sahih, it occurred previously at 7292, and Bukhari narrated something similar to it in 4/152, in the Book of the Beginning of Creation, chapter on the description of Iblis, and Muslim in 4/2293, number 2994, in the Book of Asceticism, chapter on blessing one who sneezes.