Jami` at-Tirmidhi Book 43, Hadith 9
that two men sneezed in the presence of the Prophet (ﷺ); he responded to one of them and did not respond to the other. The one who was not responded to said: "O Messenger of Allah! You responded to this person and did not respond to me?' So the Messenger of Allah (ﷺ) said: "He praised Allah while you did not praise Him."
(Another chain) from 'Ali from the Prophet (ﷺ) with similar meaning.
from his father: "A man sneezed in the presence of the Messenger of Allah (ﷺ) while I was present, so the Messenger of Allah (ﷺ) said: 'Yarhamukallah (May Allah have mercy upon you).' Then he sneezed a second and third time. So the Messenger of Allah (ﷺ) said: "This man is suffering from a cold.'"