Jami` at-Tirmidhi Book 43, Hadith 17
that the Messenger of Allah (ﷺ) said: "Indeed Allah loves sneezing and He dislikes the yawn. So when one of you sneezes and says 'Al-Hamdulillah (All praise is due to Allah),' then it is a right due from every one who hears him to say: 'Yarhamukallah (May Allah have mercy upon you)' As for yawning then when one of you yawns let him suppress it as much as possible and not say: "Hah Hah' for that is only from Ash-Shaitan laughing at him."
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."
from 'Adi - and he is Ibn Thabit - from his father, from his grandfather - : "Sneezing, dozing and yawning during Salat, and menstruation, regurgitation and nosebleeds are from Ash-Shaitan."