Sahih Muslim 7486
صحيح مسلم#7486SahihAnas b. Malik reported that two persons sneezed in the presence of Allah's Messenger (ﷺ). He (the Messenger of Allah) invoked mercy for one, and did not invoke for the other. The one for whom he had not prayed said:So and so sneezed and you said: May Allah have mercy upon you. I also sneezed but you did not utter these words for me. Thereupon he (the Holy Prophet) said: That person praised Allah, and you did not praise Allah
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 55:69