Sunan At-Tirmidhi

Narrated Abu Hurairah:that the Messenger of Allah (ﷺ) said: ""The sneeze is from Allah and the yawn is from Ash-Shaitan. So when one of you yawns let him cover his mouth with his hand. For when he says 'Ah, Ah' Ash-Shaitan laughs from inside his opening."" [And indeed Allah loves the sneeze and He dislikes the Yawn, so when a man says Ah, Ah when yawning, indeed Ash-Shaitan laughs from inside his opening]