بُلُوغُ الْمَرَامِ
Bulugh al-Maram 250
The Book of Prayer
وَعَنْ أَبِي هُرَيْرَةَ - رضى الله عنه - أَنَّ اَلنَّبِيَّ - صلى الله عليه وسلم -قَالَ : { اَلتَّثَاؤُبُ مِنْ اَلشَّيْطَانِ فَإِذَا تَثَاءَبَ أَحَدُكُمْ فَلْيَكْظِمْ مَا اِسْتَطَاعَ } رَوَاهُ مُسْلِمٌ [1]
Narrated Abu Hurairah (RA): The Prophet (ﷺ) said: "Yawning is caused by the devil, so when one of you yawns he must repress it as much as he can." [Reported by Muslim].
Sunnah.com reference: Book 2, Hadith 120