(128) باب إِذَا تَثَاوَبَ فَلْيَضَعْ يَدَهُ عَلَى فِيهِ
Narrated Abu Huraira:
The Prophet (ﷺ) said, "Allah loves sneezing but dislikes yawning; so if anyone of you sneezes and then praises Allah, every Muslim who hears him (praising Allah) has to say Tashmit to him. But as regards yawning, it is from Satan, so if one of you yawns, he should try his best to stop it, for when anyone of you yawns, Satan laughs at him."
Reference: Sahih al-Bukhari 6226
In-book reference: Book 78, Hadith 250
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 8, Book 73, Hadith 245